BACKGROUND OF THE INVENTION It is well known for lubricating oils to contain a number of additives used to protect the engine from wear, the accumulation of sludge and filter plugging. Common additives for engine lubricating oils are zinc alkyldithiophosphate (ZDDP) an antiwear additive, and overbased calcium sulphonate detergents. It is believed that ZDDP antiwear additives protect the engine by forming a protective film on metal surfaces. Typical treatment quantities of ZDDP range from 1 to 2 weight percent based on the total weight of the lubricant. Detergents such as overbased calcium sulphonate help keep the engine parts clean of soot and other deposits, and offer an alkalinity reserve. Typical treatment quantities of detergents range from 0.05 to 10 weight percent based on the total weight of the lubricant.

In recent years phosphates and sulphonates derived from engine lubricants have been shown to contribute in part to particulate emissions.

Further, sulphur and phosphorus tend to poison the NOx catalysts used in catalytic converters, resulting in a reduction in performance of said catalysts.

Any reduction in the performance of catalytic converters tends to result in increased amounts of greenhouse gases such as nitric oxide and/or sulphur oxides. However, reducing the amount phosphates and sulphonates by decreasing the amount of ZDDP and/or calcium sulphonate detergents will increase the amount of wear in an engine especially on engine parts with high

loading for instance in the valve train and increase the amount of sludge formed. Conversely reducing the amount phosphates and sulphonates will decrease filter plugging because divalent metals such as zinc and calcium are known to help form material capable of plugging filters, for instance, sulphonated ash.

The valve train metal parts are often iron or steel and these are chemically or physically modified to provide better antiwear performance. The process often involves heating the metal part to above about 600°C followed by rapid cooling (or quenching) in water and/or an oil of lubricating viscosity.

The metal part is then suitable for use and provides good protection against wear in the presence of antiwear additives such as ZDDP. However ZDDP has the disadvantages mentioned above.

Therefore there is a need for an engine part to be lubricated with a composition capable of reducing sulphur and phosphorus content without having an adverse effect on antiwear performance, sludge formation or increased filter plugging.

It would be desirable to have a lubricated part capable of decreasing wear of said part. The present invention provides a lubricated part capable of decreasing wear of said part.

It would be desirable to have a lubricated part capable of decreasing filter plugging. The present invention provides a lubricated part capable of decreasing filter plugging.

It would be desirable to have a lubricated part capable of decreasing sludge formation. The present invention provides a lubricated part capable of decreasing sludge formation.

It would be desirable to have a lubricated part capable of decreasing phosphorus emissions. The present invention provides a lubricated part capable of decreasing phosphorus emissions.

It would be desirable to have a lubricated part capable of decreasing sulphur emissions. The present invention provides a lubricated part capable of decreasing sulphur emissions.

It would be desirable to have a lubricated part capable of decreasing the amount of sulphonated ash. The present invention provides a lubricated part capable of decreasing the amount of sulphonated ash.

SUMMARY OF THE INVENTION The present invention provides a lubricated part comprising: (a) a part with at least a partial hard surface coating of average thickness less than about 25 micrometres, said coating containing at least one moiety selected from the group consisting of silicides, nitrides, carbides, borides, oxides, sulphides and mixtures thereof; (b) a detergent selected from at least one of the group consisting of a phenate salt, a sulphonate salt, a salixarate salt and mixtures thereof ; and (c) an oil of lubricating viscosity.

The invention further provides a lubricated part comprising: (a) a part with at least a partial hard surface coating of average thickness less than about 25 micrometres, said coating containing at least one tungsten moiety selected from the group consisting of silicides, nitrides, carbides, borides, oxides, sulphides and mixtures thereof; (b) a detergent package comprising: (i) a phenate salt; (ii) a sulphonate salt; and (c) an oil of lubricating viscosity.

The invention further provides a lubricated part comprising: (a) a part with at least a partial hard surface coating of average thickness less than about 25 micrometres, said coating containing at least one chromium moiety selected from the group consisting of silicides, nitrides, carbides, borides, oxides, sulphides and mixtures thereof; (b) a salixarate salt detergent ; and (c) an oil of lubricating viscosity.

The invention further provides a method for lubricating a part, wherein the lubricated part has at least one property selected from the group consisting of decreased wear, decreased filter plugging, decreased sludge formation, decreased

phosphorus emissions, decreased sulphur emissions, decreased sulphated ash formation and mixtures thereof; the method comprising a lubricated part comprising : (a) a part with at least a partial hard surface coating of average thickness less than about 25 micrometres, said coating containing at least one moiety selected from the group consisting of silicides, nitrides, carbides, borides, oxides, sulphides and mixtures thereof; (b) a detergent selected from at least one of the group consisting of a phenate salt, a sulphonate salt, a salixarate salt and mixtures thereof; and (c) an oil of lubricating viscosity.

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a lubricated part comprising: (a) a part with at least a partial hard surface coating of average thickness less than about 25 micrometres, said coating containing at least one moiety selected from the group consisting of silicides, nitrides, carbides, borides, oxides, sulphides and mixtures thereof ; (b) a detergent selected from at least one of the group consisting of a phenate salt, a sulphonate salt, a salixarate salt and mixtures thereof; and (c) an oil of lubricating viscosity.

In one aspect of the invention provides a lubricated part comprising: (a) a part with at least a partial hard surface coating of average thickness less than about 25 micrometres, said coating containing at least one tungsten moiety selected from the group consisting of silicides, nitrides, carbides, borides, oxides, sulphides and mixtures thereof; (b) a detergent package comprising: (i) a phenate salt; (ii) a sulphonate salt; and (c) an oil of lubricating viscosity.

In one aspect of the invention provides a lubricated part comprising: (a) a part with at least a partial hard surface coating of average thickness less than about 25 micrometres, said coating containing at least one chromium

moiety selected from the group consisting of silicides, nitrides, carbides, borides, oxides, sulphides and mixtures thereof; (b) a salixarate salt detergent; and (c) an oil of lubricating viscosity.

In one aspect of the invention provides a method for lubricating a part, wherein the lubricated part has at least one property selected from the group consisting of decreased wear, decreased filter plugging, decreased sludge formation, decreased phosphorus emissions, decreased sulphur emissions, decreased sulphated ash formation and mixtures thereof; the method comprising a lubricated part comprising: (a) a part with at least a partial hard surface coating of average thickness less than about 25 micrometres, said coating containing at least one moiety selected from the group consisting of silicides, nitrides, carbides, borides, oxides, sulphides and mixtures thereof; (b) a detergent selected from at least one of the group consisting of a phenate salt, a sulphonate salt, a salixarate salt and mixtures thereof; and (c) an oil of lubricating viscosity.

In one aspect of the invention provides a method for lubricating a part, wherein the lubricated part has at least one property selected from the group consisting of decreased wear, decreased filter plugging, decreased sludge formation, decreased phosphorus emissions, decreased sulphur emissions, decreased sulphated ash formation and mixtures thereof; the method comprising a lubricated part comprising: (a) a part with at least a partial hard surface coating of average thickness less than about 25 micrometres, said coating containing at least one tungsten moiety selected from the group consisting of silicides, nitrides, carbides, borides, oxides, sulphides and mixtures thereof; (b) a detergent package comprising : (i) a phenate salt; (ii) a sulphonate salt; and (c) an oil of lubricating viscosity.

In one aspect of the invention provides a method for lubricating a part, wherein the lubricated part has at least one property selected from the group consisting of decreased wear, decreased filter plugging, decreased sludge formation, decreased phosphorus emissions, decreased sulphur emissions, decreased sulphated ash formation and mixtures thereof ; the method comprising a lubricated part comprising: (a) a part with at least a partial hard surface coating of average thickness less than about 25 micrometres, said coating containing at least one chromium moiety selected from the group consisting of silicides, nitrides, carbides, borides, oxides, sulphides and mixtures thereof ; (b) a salixarate salt detergent; and (c) an oil of lubricating viscosity.

Lubricated Part The lubricated part can be metal or a non-metal, for instance a polymeric material or a ceramic material, although metal parts are preferred. Typically the lubricated part can be located in an engine, the drive train or other areas where there can be boundary lubrication. Preferably the lubricated part can be located in an engine. Often the lubricated part can include parts within the engine such as a crankshaft, a piston, a piston ring, auxiliary components the valve train, fuel injector train or mixtures thereof. Preferably the lubricated part can include the valve train components such as a camshaft, a cam follower, a valve adjuster, a crosshead, a rocker arm, a rocker arm pad, a lobe, a push rod or mixtures thereof; or the fuel injector train such as an injector adjuster. In one embodiment the lubricated part is the rocker arm and rocker arm pads. In one embodiment the lubricated part is the cam follower and the cam lobe. In one embodiment the lubricated part is the crosshead. In one embodiment the lubricated part is the valve adjuster. In one embodiment the lubricated part is the injector adjuster.

Partial Hard Surface Coating The partial hard surface coating of the invention are known in the art and are typically used to in areas where there is a need for boundary lubrication, for instance, metal to metal contact. The partial hard surface coating is applied to the surface in a sufficient amount to cover the contact area i. e. where boundary

lubrication is required. Typically a partial hard surface will have an average thickness less than about 25 micrometres, preferably less than about 20 micrometres, more preferably less than about 15 micrometres, even more preferably less than about 12 micrometres and even more preferably less than about 8 micrometres.

Often the average coating thickness will be in the range about 50 nanometres to about 25 micrometres, preferably about 100 nanometres to about 20 micrometres, more preferably about 300 nanometres to about 15 micrometres, even more preferably about 600 nanometres to about 10 micrometres and even more preferably about 900 nanometres to about 5 micrometres. In one embodiment the average coating thickness is between about 3 micrometres and about 5 micrometres. In one embodiment the average coating thickness is between about 2 micrometres and about 4 micrometres.

The partial hard surface coating contains at least one moiety selected from the group consisting of silicides, nitrides, carbides, borides, oxides, sulphides and mixtures thereof. Preferably the coating contains at least one moiety selected from the group consisting of nitrides, carbides and mixtures thereof. In one embodiment the coating contains nitrides. In one embodiment the coating contains carbides. In one embodiment the coating can include sulphides such as molybdenum sulphide.

In one embodiment the coating can be substantially free of to free of sulphides such as molybdenum sulphide. In one embodiment the coating can include oxides such as tungsten oxide. In one embodiment the coating can be substantially free of to free of oxides such as tungsten oxide.

Typically the silicides, nitrides, carbides, borides, oxides and sulphides incorporate at least one metal selected from the group consisting of Group IVb of the periodic table, Group Vb of the periodic table Group VIb of the periodic table and mixtures thereof. Examples of suitable metals include chromium, molybdenum, tungsten, vanadium, titanium or mixtures thereof. Preferably the metals are selected from the group consisting of chromium, tungsten, vanadium and mixtures thereof.

In one embodiment the metal is chromium. In one embodiment the metal is tungsten.

The partial hard surface coating can be selected from at least one of vanadium silicide, vanadium nitride, vanadium carbide, vanadium boride, vanadium oxide, vanadium sulphide, tungsten silicide, tungsten nitride, tungsten carbide, tungsten boride, tungsten oxide, tungsten sulphide, chromium silicide, chromium nitride, chromium carbide, chromium boride, chromium oxide, chromium sulphide and mixtures thereof. Typically the partial hard surface coating will have a Vickers hardness (VHN) from about 700 to about 2500, preferably about 800 to about 2000 and even more preferably about 900 to about 1900. In one embodiment the VHN is from about 900 to about 1350.

In one embodiment the partial hard surface coating is tungsten carbide.

Typically tungsten carbide has a VHN hardness of 700 or more, preferably 850 or more and more preferably 950 or more. In one embodiment the hardness is about 1000. In one embodiment the average coating thickness is between about 2 to about 4 micrometres. A typical commercially available tungsten carbide coating suitable for the invention is Balinitt) This tungsten carbide coating is available from Balzers Limited.

In one embodiment the partial hard surface coating is chromium nitride.

Typically chromium nitride has a hardness of 1200 or more, preferably 1450 or more and more preferably 1600 or more Vickers hardness (VHN). In one embodiment the hardness is about 1750 VHN. In one embodiment the average coating thickness is between about 3 to about 5 micrometres. A typical commercially available chromium nitride coating suitable for the invention is Balinit@D. This chromium nitride coating is available from Balzers Limited.

The partial hard surface coating can be deposited onto the part to be lubricated as a singular layer or as part of multi layer. A multi layer can have one or more of the coatings described above, for example a chromium nitride layer and then a tungsten carbide layer. Also in some instances an adhesive layer may be required. In one embodiment the partial hard surface coating is deposited as a jungle layer.

The partial hard surface coating can be deposited onto the part to be lubricated by a number of techniques, for instance, physical vapour deposition (PVD), chemical vapour deposition (CVD), ion beam deposition (also referred to as

IBD or IBAD), ion beam enhanced deposition (IBED) and plasma induced immersion process techniques. Preferably the partial hard surface coating can be deposited onto the part to be lubricated by physical vapour deposition. Typical physical vapour deposition techniques include PVD ion plating or PVD magnetron sputtering. In one embodiment the partial hard surface coating is deposited by PVD ion plating. In one embodiment the partial hard surface coating is deposited by PVD magnetron sputtering.

As used herein, the term"hydrocarbyl substituent"or"hydrocarbyl group"is used in its ordinary sense, which is well-known to those skilled in the art. Specifically, it refers to a group having a carbon atom directly attached to the remainder of the molecule and having predominantly hydrocarbon character. Examples of hydrocarbyl groups include: hydrocarbon substituents, that is, aliphatic (e. g., alkyl or alkenyl), alicyclic (e. g., cycloalkyl, cycloalkenyl) substituents, and aromatic-, aliphatic-, and alicyclic-substituted aromatic substituents, as well as cyclic substituents wherein the ring is completed through another portion of the molecule (e. g., two substituents together form a ring); substituted hydrocarbon substituents, that is, substituents containing non-hydrocarbon groups which, in the context of this invention, do not alter the <BR> <BR> predominantly hydrocarbon nature of the substituent (e. g. , halo (especially chloro and fluoro), hydroxy, alkoxy, mercapto, alkylmercapto, nitro, nitroso, and sulfoxy); hetero substituents, that is, substituents which, while having a predominantly hydrocarbon character, in the context of this invention, contain other than carbon in a ring or chain otherwise composed of carbon atoms.

Heteroatoms include sulfur, oxygen, nitrogen, and encompass substituents as pyridyl, furyl, thienyl and imidazolyl. In general, no more than two, preferably no more than one, non-hydrocarbon substituent will be present for every ten carbon atoms in the hydrocarbyl group; typically, there will be no non- hydrocarbon substituents in the hydrocarbyl group.

Sulphonate Salt Detergent The substrate of the sulphonate detergent of the composition can be represented by the formula (Rl) k-Z-SO3M : wherein, each R'is independently an alkyl, cycloallcyl, aryl, acyl, or other hydrocarbyl group with a 6 to 40, preferably 8 to 25 and even more preferably 9 to 20 carbon atoms ; Z can be independently a cyclic or acyclic hydrocarbon group; M can be hydrogen, a valence of a metal ion, an ammonium ion and mixtures thereof, provided hydrogen is present on less than 50%, preferably less than 30%, more preferably less than 20%, even more preferably less than 10% and even more preferably less than 5% of the available M entities; and k is an integer between 1 and 5, for example 1, 2,3, 4,5 or mixtures thereof. Preferably k is between 1 and 3, more preferably 1 or 2 and even more preferably 1.

In one embodiment k is 1 and Ru ils a branched alkyl group with 6 to 40 carbon atoms. In one embodiment k is 1 and R'is a linear alkyl group with 6 to 40 carbon atoms.

The most preferred sulphonate components are calcium polypropene benzenesulphonate; and calcium monoalkyl-and/or dialkyl-benzenesulphonate wherein the alkyl groups contain at least 10 carbon atoms, for example, 11 carbon atoms, 12 carbon atoms, 13 carbon atoms, 14 carbon atoms, 15 carbon atoms and mixtures thereof.

When M is a valence of a metal ion, the metal can be monovalent, divalent, trivalent or mixtures of such metals. When monovalent, the metal M can be an alkali metal, preferably lithium, sodium, or potassium; and more preferably potassium, which can be used alone or in combination with other metals. When divalent, the metal M can be an alkaline earth metal, preferably magnesium, calcium, barium or mixtures of such metals, more preferably calcium, which can be used alone or in combination with other metals. When trivalent, the metal M can be aluminum, which can be used alone or in combination with other metals. In one embodiment the metal is an alkaline earth metal. In one embodiment the metal is calcium, which can be used alone or in combination with other metals.

When Z is cyclic hydrocarbon group, suitable groups include phenyl or fused bicyclic groups such as naphthalene, indenyl, indanyl, bicyclopentadienyl and mixtures thereof. Although Z can be a fused bicyclic ring, benzene rings are preferred.

When Z is an acyclic hydrocarbon group, the carbon chain can be linear or branched, although linear is preferred. Suitable groups include derivatives of carboxylic acids containing 7 to 30, preferably 7 to 20, more preferably 8 to 20 and even more preferably 8 to 15 carbon atoms. Further the chain can be saturated or unsaturated, although saturated is preferred.

Typically an overbased sulphonate detergent has a TBN (total base number) in the range of about 300 to about 600, preferably about 310 to about 580, more preferably about 320 to about 540 and even more preferably about 330 to about 510. In one embodiment the overbased sulphonate detergent has a TBN of about 400. The overbased sulphonate detergent may be used alone or with other detergents.

The sulphonate detergent can overbased or non-overbased, although overbased is preferred. Overbased material, otherwise referred to as overbased or superbased salts, are generally single phase, homogeneous Newtonian systems characterised by a metal content in excess of that which would be present for neutralisation according to the stoichiometry of the metal and the particular acidic organic compound reacted with the metal. The overbased materials are prepared by reacting an acidic material (typically an inorganic acid or lower carboxylic acid, preferably carbon dioxide) with a mixture comprising an acidic organic compound, a reaction medium comprising at least one inert, organic solvent (mineral oil, naphtha, toluene, xylene, etc. ) for said acidic organic material, a stoichiometric excess of a metal base, and a promoter such as a phenol or alcohol. A mixture of alcohols typically contains methanol and at least one alcohol with 2 to 7 carbon atoms. The acidic material will normally have a sufficient number of carbon atoms to provide a degree of solubility in oil. The amount of excess metal is commonly expressed in terms of metal ratio. The term"metal ratio"is the ratio of the total equivalents of the metal to the equivalents of the acidic organic compound. A neutral metal salt

has a metal ratio of one. A salt having 4.5 times as much metal as present in a normal salt will have metal excess of 3.5 equivalents, or a ratio of 4.5.

When present, the sulphonate detergent is typically present at about 0.05 to about 20, preferably about 0.1 to about 10, and more preferably about 0.2 to about 8 and even more preferably about 0.5 to about 5 weight percent of the lubricating oil composition.

Salixarate Salt Detergent The substrate of the salixarate detergent of the invention can be represented by a substantially linear compound comprising at least one unit of the formulae (I) or (II): each end of the compound having a terminal group of formulae (III) or (IV):

(III) (IV) such groups being linked by divalent bridging groups A, which may be the same or different for each linkage ; wherein in formulas (I)-(IV) R3 is hydrogen or a hydrocarbyl group; R2 is hydroxyl or a hydrocarbyl group and j is 0,1, or 2; R6 is hydrogen, a hydrocarbyl group, or a hetero-substituted hydrocarbyl group; either R is hydroxyl and Rs and R7 are independently either hydrogen, a hydrocarbyl group, or hetero-substituted hydrocarbyl group, or else R 5 and R7 are both hydroxyl and R4 is hydrogen, a hydrocarbyl group, or a hetero- substituted hydrocarbyl group; provided that at least one of R4, R5, R6 and R7 is hydrocarbyl containing at least 8 carbon atoms; and wherein the molecules on average contain at least one of unit (1) or (III) and at least one of unit (II) or (IV) and the ratio of the total number of units (I) and (III) to the total number of units of (II) and (IV) in the composition is about 0.1 : 1 to about 2: 1.

The divalent bridging group"A, "which may be the same or different in each occurrence, includes-CH2- (methylene bridge) and-CH20CH2- (ether bridge), either of which may be derived from formaldehyde or a formaldehyde equivalent (e. g. , paraform, formalin).

Salixarate derivatives and methods of their preparation are described in greater detail in U. S. patent number 6,200, 936 and PCT Publication WO 01/56968. It is believed that the salixarate derivatives have a predominantly linear, rather than macrocyclic, structure, although both structures are intended to be encompassed by the term"salixarate." Preparative Example. Overbased Salixarate Step (a). A reactor is charged with 15 kg (23.3 moles) of polyisobutenyl (Mn 550) substituted phenol and 10.7 kg 150 N mineral oil. The materials are heated, under nitrogen, to 35°C, then 120 g (1.07 moles) aqueous KOH is added via a pump and charge line, which is subsequently washed into the reactor with 100 mL distilled water. The mixture is heated to 75°C over 0.5 hour and 2.6 kg (32. 1 moles) of 37% aqueous formaldehyde is added via a pump and charge line over 0.5 hour, subsequently washed into the reactor with 300 mL distilled water. The mixture is held at temperature for 2 hours, whereupon 1. 65 kg salicylic acid (12 moles) is added followed by heating to 99°C and reflux. The reaction mixture is further heated to 140°C over 1 hour, removing 2.6 L aqueous distillate. The mixture is maintained at 140°C for 1.5 hour at atmospheric pressure, followed by 0.5 hour at 60 kPa (0.6 bar), collecting some additional aqueous distillate.

Step (b). A reactor is charged with 13.0 kg (8.95 moles) of the cooled product of step (a), 2.33 kg (31.5 moles) Ca (OH) 2, and 450 g ethylene glycol.

While stirring, 7. 38 kg of 2-ethylhexanol are added over 0.3 hours. The mixture is heated at 95°C at reduced pressure (80 kPa to 44 kPa [0.2 to 0.56 bar vacuum]) over 3/4 hour, followed by 130°C over 1/4 hour at 80 kPa (0.2 bar vacuum), during which time 0.5 L aqueous distillate is collected. An additional 2.16 kg ethylene glycol is added is added over about 0.3 hour at 125 to 130°C.

Pressure is reduced to 90 kPa (0.1 bar vacuum) and then carbon dioxide is passed into the mixture at 500 g/hour until a total of 750 g is added. After carbonation is complete, the temperature is increased to 200°C and the pressure reduced to 44 kPa (0.56 bar vacuum) and maintained for a total of about 2.2 hours, during which time 9.5 L aqueous distillate is collected. The product is an overbased calcium salixarate.

It is believed that a significant fraction of salixarate molecules (prior to neutralisation) may be represented on average by the following formula:

wherein each R can be the same or different, and are an alkyl group, and, in a preferred embodiment, is a polyisobutene group (especially of molecular weight 200 to 1,000, or about 550). Significant amounts of di-or trinuclear species may also be present containing one salicylic end group of formula (III).

The salixarate detergent may be used alone or with other detergents.

When present, the salixarate detergent is typically present at about 0.05 to about 20, preferably about 0.1 to about 10, and more preferably about 0.2 to about 8 and even more preferably about 0.5 to about 5 weight percent of the lubricating oil composition.

Phenate Salt Detergent The substrate of the phenate detergent of the composition can be represented by the formulae:

wherein the number of sulphur atoms in formula (VI) y, can be in the range from 1 to 8, preferably 1 to 6 and even more preferably 1 to 4; the number of (CRi°CRll) moieties y in formula (VII), can be in the range from 0 to 8, preferably 0 to 4 and even more preferably 0 to 2. In one embodiment y=1 in formula (VI), and the phenate detergent is often described in the art as a sulphur containing phenate. In one embodiment y=0 in formula (VII), and the <BR> <BR> phenate detergent is often described in the art as"normal. "In one embodiment y=l in formula (VII), and the phenate detergent is often described in the art as"alkylene coupled", especially"methylene coupled." R9 can be the same or different and are independently hydrogen or a hydrocarbyl group. When R9 is hydrocarbyl group, a preferred group is an alkyl group, and, in a more preferred embodiment, is a polyisobutene group (especially of molecular weight 200 to 1,000, or about 550) ; T is hydrogen or an (S) y linkage terminating in hydrogen, an ion or a non-phenolic hydrocarbyl group ; and M is as described above for the sulphonate detergent. x is an integer and present in a sufficient number of times to form oligomers of hydrocarbyl phenol. Oligomers are described as dimers, trimers, tetramer, pentamers and hexamers when x is equal to 0,1, 2,3, 4,5 and 6 respectively to form a substrate. Typically the number of oligomers represented by x can be in the range from 0 to 10, preferably 0 to 9, more preferably 0 to 8, even more even more preferably 0 to 6 and even more preferably 0 to 4.

The number of R9 and/or substituents other than hydrogen on each hydrocarbyl phenol ring w, can be in the range from 0 to 3, more preferably 1 to 2 and even more preferably 1, provided at least one hydrocarbyl group is

present on an oligomer. In one embodiment w is 1 and located at para position relative to the OM group. Typically, the minimum number of carbon atoms present on all hydrocarbyl groups to ensure oil solubility can be 8 or preferably 9. When two or more hydrocarbyl groups are present in the same substrate molecule, they may be the same or different. Rl° and Rll can be hydrogen or hydrocarbyl or mixtures thereof, preferably at least one is hydrogen and even more preferably both are hydrogen.

Typically the sulphur containing phenate detergent has a TBN in the range of 30 to 300, preferably 80 to 290, more preferably 100 to 280 and even more preferably 120 to 270. In one embodiment the sulphur containing phenate detergent has a TBN of about 250. The sulphur containing phenate detergent may be used alone or with other sulphur containing phenate detergents.

When present, the phenate detergent is typically present at about 0.05 to about 20, preferably about 0.1 to about 10, and more preferably about 0.2 to about 8 and even more preferably about 0.5 to about 5 weight percent of the lubricating oil composition.

Oils of Lubricating Viscosity The lubricating oil composition of the present invention can be added to an oil of lubricating viscosity. The oil includes natural and synthetic oils, oil derived from hydrocracking, hydrogenation, hydrofinishing, unrefined, refined and re-refined oils, or mixtures thereof.

Unrefined oils are those obtained directly from a natural or synthetic source generally without (or with little) further purification treatment.

Refined oils are similar to the unrefined oils except they have been further treated in one or more purification steps to improve one or more properties. Purification techniques are known in the art and include solvent extraction, secondary distillation, acid or base extraction, filtration, percolation and the like.

Re-refined oils are also known as reclaimed or reprocessed oils, and are obtained by processes similar to those used to obtain refined oils and often are additionally processed by techniques directed to removal of spent additives and oil breakdown products.

Natural oils useful in making the inventive lubricants include animal oils, vegetable oils (e. g. , castor oil, lard oil), mineral lubricating oils such as liquid petroleum oils and solvent-treated or acid-treated mineral lubricating oils of the paraffinic, naphthenic or mixed paraffinic-naphthenic types and oils derived from coal or shale or mixtures thereof.

Synthetic lubricating oils are useful and include hydrocarbon oils such as polymerised and interpolymerised olefins (e. g., polybutylenes, polypropylenes, propyleneisobutylene copolymers); poly (l-hexenes), poly (l- octenes), poly (l-decenes), and mixtures thereof; alkyl-benzenes (e. g. dodecylbenzenes, tetradecylbenzenes, dinonylbenzenes, di- (2-ethylhexyl)- benzenes); polyphenyls (e. g., biphenyls, terphenyls, alkylated polyphenyls); alkylated diphenyl ethers and alkylated diphenyl sulphides and the derivatives, analogs and homologs thereof or mixtures thereof.

Other synthetic lubricating oils include but are not limited to polyol esters, liquid esters of phosphorus-containing acids (e. g., tricresyl phosphate, trioctyl phosphate, and the diethyl ester of decane phosphonic acid), and polymeric tetrahydrofurans. Synthetic oils may be produced by Fischer- Tropsch reactions and typically may be hydroisomerised Fischer-Tropsch hydrocarbons or waxes.

Oils of lubricating viscosity can also be defined as specified in the American Petroleum Institute (API) Base Oil Interchangeability Guidelines.

The five base oil groups are as follows: Group I (sulphur content >0.03 wt %, and/or <90 wt % saturates, viscosity index 80-120) ; Group II (sulphur content <0. 03 wt %, and >90 wt % saturates, viscosity index 80-120) ; Group III (sulphur content <0. 03 wt %, and >90 wt % saturates, viscosity index >120) ; <BR> <BR> Group IV (all polyalphaolefins (PAO's) ) ; and Group V (all others not included in Groups I, II, III, or IV). The oil of lubricating viscosity is selected from the group consisting of API Group I, II, III, IV, V oil and mixtures thereof.

Preferably the oil of lubricating viscosity is selected from the group consisting of API Group II, III, or IV oil and mixtures thereof. If the oil of lubricating viscosity is an API Group II, III, or IV oil there can be up to a maximum of about 49.9 wt %, preferably up to a maximum of about 40 wt %, more

preferably up to a maximum of about 30 wt %, even more preferably up to a maximum of about 20 wt %, even more preferably up to a maximum of about 10 wt % and even more preferably up to a maximum of about 5 wt % of the lubricating oil an API Group I or V oil.

The oil of lubricating viscosity is typically present at about 5 to about 99. 8, preferably about 42 to about 98.7, and more preferably about 55.2 to about 97.3 and even more preferably about 69.3 to about 95.4 weight percent of the lubricating oil composition.

If the present invention is in the form of a concentrate (which can be combined with additional oil to form, in whole or in part, a finished lubricant), the ratio of each of the above-mentioned dispersant, as well as other components, to diluent oil is typically in the range of about 80: 20 to about 10: 90 by weight.

Metal Hydrocarbyl Dithiophosphate The invention can further contain a metal hydrocarbyl dithiophosphate that can be represented by the formula: wherein R12 and R13 are independently hydrogen, hydrocarbyl groups or mixtures thereof, provided that at least one of R12 and R13 is a hydrocarbyl group, preferably alkyl or cycloalkyl with 1 to about 30, preferably about 2 to about 20 and even more preferably about 2 to about 15 carbon atoms.

M'is a metal, and n is an integer equal to the available valence of M'.

M'is mono-or di-or tri-valent, preferably divalent, more preferably a divalent transition metal. In one embodiment M'is zinc. In one embodiment M'is calcium. In one embodiment M'is barium.

Examples of suitable zinc hydrocarbyl dithiophosphates (often referred to as ZDDP, ZDP or ZDTP) can include zinc isopropyl methylamyl dithiophosphate, zinc isopropyl isooctyl dithiophosphate, barium di- (nonyl)- dithiophosphate, zinc di- (cyclohexyl) dithiophosphate, zinc di- (isobutyl)

dithiophosphate, calcium di- (hexyl) dithiophosphate, zinc isobutyl isoamyl dithiophosphate, zinc isopropyl n-butyl dithiophosphate, isobutyl primary amyl dithiophosphate, methylamyl dithiophosphate, isopropyl 2-ethylhexyl dithiophosphate, and mixtures thereof. Other suitable metal hydrocarbyl dithiophosphates include barium di- (nonyl)-dithiophosphate, calcium di- (hexyl) dithiophosphate and mixtures thereof.

The metal hydrocarbyl dithiophosphates can typically be present at 0 to about 5, preferably about 0.01 to about 3, and more preferably about 0.05 to about 0.8 and even more preferably about 0.07 to about 0.7 wt % of the lubricating oil composition. In one embodiment the metal hydrocarbyl dithiophosphates are present at less than 1 wt % of the lubricating oil composition. In one embodiment the metal hydrocarbyl dithiophosphates are present at less than 0.8 wt % of the lubricating oil composition. In one embodiment the metal hydrocarbyl dithiophosphates are present at less than 0.6 wt % of the lubricating oil composition. In one embodiment the metal hydrocarbyl dithiophosphates can be present at about 0.5 weight percent of the lubricating oil composition.

Borated Ester The invention may further contain a borate ester friction modifier. The borate ester can be prepared by the reaction of a boron compound and at least one compound selected from epoxy compounds, halohydrin compounds, epihalohydrin compounds, alcohols and mixtures thereof. Typically the alcohols include monohydric alcohols, dihydric alcohols, trihydric alcohols or higher alcohols.

Hereinafter"epoxy compound or equivalent is used when referring to"at least one compound selected from epoxy compounds, halohydrin compounds, epihalohydrin compounds, alcohols and mixtures thereof. " Boron compounds suitable for preparing the borate ester include the various forms selected from the group consisting of boric acid (including metaboric acid, HB02, orthoboric acid, H3BO3, and tetraboric acid, H2B407), boric oxide, boron trioxide and alkyi berates. The borate ester can also be prepared from boron halides.

The borate ester formed by the reaction of a boron compound and an epoxy compound or equivalent can be represented by at least one formula selected from:

wherein Rl4, Rls and Rl6 can be hydrogen or hydrocarbyl groups provided at least one, preferably at least two of R14, Rls and R16 are hydrocarbyl groups. In one embodiment, R14 is a hydrocarbyl group; and Rls and Rl6 are hydrogen. In one embodiment, R14 and Rls are hydrocarbyl groups and R16 is hydrogen. In one embodiment R14, Rls and R16 are all hydrocarbyl groups. The hydrocarbyl groups can be alkyl, aryl or cycloalkyl when any 2 adjacent R groups are connected in a ring. When alkyl, the group can be saturated or unsaturated, although unsaturated is preferred. In one embodiment the hydrocarbyl group is cyclic. In one embodiment the hydrocarbyl groups are mixtures of alkyl and cycloalkyl.

Typically there is no upper limit on the number of carbon atoms, but a practical limit is about 500, preferably about 400, more preferably about 200, even more preferably about 100 or about 60. For example the number of carbon atoms present in Rl4, Rls and R16 can be 1 to about 60, preferably 1 to about 40 and more preferably 1 to about 30 carbon atoms, provided the total number of carbon atoms in Rl4, Rls and R16 is about 9 or more, preferably about 10 or more, more preferably about 12 or more or about 14 or more.

In one embodiment R14, Rls and R16 are all hydrocarbyl groups containing 1 to about 30 carbon atoms, provided the total number of carbon atoms in R14, Rls and R16 is about 9 or more.

R17 to R23 inclusive can be hydrogen or hydrocarbyl groups, provided at least one of Rl7 to R2'and/or R2'to R 23 is a hydrocarbyl group. R24 to R29 inclusive are hydrocarbyl groups or hydrogen, although hydrocarbyl groups are preferred; and R30 can be hydrogen or a hydrocarbyl group, although hydrogen is preferred. The hydrocarbyl group definition for R17 to R30 inclusive is the same as the definition given for R14, Ris and R.

Examples of groups suitable for R14 to WO inclusive include isopropyl, n-butyl, isobutyl, amyl, 2-pentenyl, 4-methyl-2-pentyl, 2-ethyl-l-hexyl, 2- ethylhexyl, heptyl, isooctyl, nonyl, decyl, undecyl, dodecenyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl and eicosyl groups.

The borated ester can be present from about 0 to about 20, preferably about 0.1 to about 15, more preferably about 0.3 to about 10 and even more preferably about 0.5 to about 5 weight percent of the lubricating oil composition.

The epoxy compounds useful for preparing the borate ester of the invention can be represented by the formulae: wherein R31 can be an allcyl chain containing 8 to 30, preferably 10 to 26 and even more preferably 12 to 22 carbon atoms; R32 can be hydrogen or an alkyl chain containing 1 to 4, preferably 1 to 2 carbon atoms, even more preferably R32 being hydrogen ; and G can be hydrogen or a halogen, that is, chlorine, bromine, iodine or fluorine or mixtures thereof, although chlorine is preferred.

Even more preferably G is hydrogen. When G is a halogen, the epoxy compounds of the invention are epihalohydrin compounds.

In one embodiment the epoxy compounds of the invention include commercial mixtures of Cl4-CI6 epoxides or C14-Clg epoxides. In one embodiment, the epoxy compounds of the invention have been purified. Examples of suitable

purified epoxy compounds can include 1,2-epoxydecane, 1, 2-epoxytmdecane, 1,2-epoxydodecane, 1, 2-epoxytridecane, 1,2-epoxybutadecane, 1,2-epoxypenta- decane, 1, 2-epoxyhexadecane, 1, 2-epoxyheptadecane,. 1,2-epoxyoctadecane, 1,2-epoxynonadecane and 1,2-epoxyicosane. Preferably purified epoxy compounds include 1,2-epoxytetradecane, 1, 2-epoxypentadecane 1,2-epoxyhexadecane 1,2- epoxyheptadecane, 1,2-epoxyoctadecane ; and more preferably 1, 2-epoxyhexa- decane.

Another group of compounds described as"epoxy compounds or equivalent" are alcohols and include monohydric alcohols, dihydric alcohols, trihydric alcohols, higher alcohols (that is, alcohols containing about 4 or more hydroxy groups) and mixtures thereof, monohydric alcohols being preferred. Typically the alcohol compounds contain about 2 to about 30, more preferably about 4 to about 26 and even more preferably about 6 to about 20 carbon atoms. The alcohol compounds can include glycerol compounds such as glycerol monooleate.

Other Performance Additives The lubricated part is lubricated using a lubricating oil composition comprising (a) at least one detergent from component (b) of the invention; an oil of lubricating viscosity from component (c) of the invention; (c) optionally a metal hydrocarbyl dithiophosphate ; (d) optionally a borate ester; and (e) other performance additives.

The other performance additives selected from the group consisting of detergents other than those of component (b) of the invention, metal deactivators, dispersants, antioxidants, antiwear agents, corrosion inhibitors, antiscuffing agents, extreme pressure agents, foam inhibitors, demulsifiers, friction modifiers other than a borate ester, viscosity modifiers, pour point depressants, fluidity modifiers and seal swelling agents. Typically, fully- formulated lubricating oil will contain one or more of these other performance additives.

The total combined amount of the other performance additives present can be from about 0 to about 30, preferably about 1 to about 25, more preferably about 2 to about 20 and even more preferably about 3 to about 15 weight percent of the lubricating oil composition. Although one or more of the

other performance additives can be present, it is common for the performance additives to ; be present in different amounts relative to each other.

Typically antioxidants and/or viscosity modifiers are the most abundant and account for about 40 or more, preferably about 55 or more, more preferably about 70 or more, even more preferably about 80 or more and even more preferably about 90 or more wt % of the other performance additives in the lubricating oil composition. Typically antioxidants are present in about 2 to about 10 wt % of the lubricating oil composition, for example, 3 wt %, 4 wt %, 5 wt % or 6 wt % ; Typically viscosity modifiers are present in about 2 to about 15 wt % of the lubricating oil composition, for example, 4 wt %, 5 wt % or 6 wt %, 7 wt % or 8 wt %.

Metal Deactivators Metal deactivators can be used to neutralise the catalytic effect of metal for promoting oxidation in lubricating oil. Examples of metal deactivators include but are not limited to derivatives of benzotriazoles, 1,2, 4-triazoles, benzimidazoles, 2-alkyldithiobenzimidazoles, 2-alkyldithiobenzothiazoles, 2- (N, N-dialkyldithiocarbamoyl) benzothiazoles, 2,5-bis (alkyl-dithio)-1, 3,4- thiadiazoles, 2,5-bis (N, N-dialkyldithiocarbamoyl)-1, 3,4-thiadiazoles, 2- alkyldithio-5-mercapto thiadiazoles and mixtures thereof. The metal deactivator may be used alone or in combination with other metal deactivators.

In one embodiment the metal deactivator is a derivative of benzotriazole. In one embodiment the metal deactivator is a 2,5-bis (alkyl-dithio)-1, 3,4- thiadiazole.

In one embodiment hydrocarbyl benzotriazoles substituted at positions 4-or 5-or 6-or 7-can be further reacted with an aldehyde and a secondary amine to form a Mannich product. Examples of suitable Mannich products include N, N-bis (heptyl)-ar-metliyl-1H-benzotriazole-1-methanamine, N, N- bis (nonyl)-ar-methyl- IH-benzotriazole-1-methanamine, N, N-bis (decyl)-ar- methyl-1 H-benzotriazole-1-methanamine, N, N-bis (undecyl)-ar-methyl-1 H- benzotriazole-1-methanamine, N, N-bis (dodecyl)-ar-methyl-1 H-benzotriazole-1- methanamine N, N-bis (2-ethylhexyl)-ar-methyl-1 H-benzotriazole-1-methan-

amine and mixtures thereof. In one embodiment the metal deactivator is N, N- bis (2-ethylhexyl)-ar-methyl-1 H-benzotriazole-1-methanamine.

In one embodiment the metal deactivator is a hydrocarbyl substituted benzotriazole compound. The benzotriazole compounds with hydrocarbyl substitutions include at least one of the following ring positions 1-or 2-or 4-or 5-or 6-or 7-. The hydrocarbyl groups contain 1 to 30, preferably 1 to 15, preferably 1 to 7 carbon atoms, and even more preferably the metal deactivator is 5-methylbenzotriazole (tolyltriazole).

In one embodiment, the metal deactivator is a 2, 5-bis (alkyl-dithio)- 1,3, 4-thiadiazole. The alkyl groups of 2,5-bis (alkyl-dithio)-1, 3, 4-thiadiazole contain 1 to about 30, preferably about 2 to about 25, more preferably 4 to about 20 and even more preferably about 6 to about 16 carbon atoms.

Examples of suitable 2,5-bis (alkyl-dithio)-1, 3,4-thiadiazoles include but are not limited to 2,5-bis (tert-octyldithio)-1, 3, 4-thiadiazole 2,5-bis (tert-nonyldithio)- 1,3, 4-thiadiazole, 2,5-bis (tert-decyldithio)-1, 3, 4-thiadiazole, 2,5-bis (tert- undecyldithio)-1, 3, 4-thiadiazole, 2,5-bis (tert-dodecyldithio)-1, 3,4-thiadiazole, <BR> <BR> 2,5-bis (tert-tridecyldithio)-1, 3,4-thiadiazole, 2,5-bis (tert-tetradecyldithio) - 1, 3, 4-thiadiazole, 2,5-bis (tert-pentadecyldithio)-1, 3, 4-thiadiazole, 2,5-bis (tert- hexadecyldithio)-1, 3, 4-thiadiazole, 2,5-bis (tert-heptadecyldithio)-1, 3,4- thiadiazole, 2,5-bis (tert-octadecyldithio)-1, 3,4-thiadiazole, 2,5-bis (tert- nonadecyldithio)-1, 3,4-thiadiazole, 2,5-bis (tert-eicosyldithio)-1, 3,4-thiadiazole and mixtures thereof. Preferably a 2,5-bis (alkyl-dithio)-1, 3, 4-thiadiazole metal deactivator can be 2,5-bis (tert-nonyldithio)-1, 3,4-thiadiazole or mixtures thereof.

Detergents Detergents other than those of component (b) of the invention are known and can include neutral or overbased, Newtonian or non-Newtonian, basic salts of alkali, alkaline earth and transition metals with one or more of carboxylic acid, phosphorus acid, mono-and/or di-thiophosphoric acid, saligenins or mixtures thereof. Commonly used metals include sodium, potassium, calcium, magnesium lithium or mixtures thereof. Most commonly used metals include sodium, magnesium and calcium.

Dispersants Dispersants are often known as ashless-type dispersants because, prior to mixing in a lubricating oil composition they do not contain ash-forming metals; and they do not normally contribute any ash forming metals when added to a lubricant and polymeric dispersants. Ashless type dispersants are characterised by a polar group attached to a relatively high molecular weight hydrocarbon chain. Typical ashless dispersants include N-substituted long chain alkenyl succinimides. Examples of N-substituted long chain alkenyl succinimides include polyisobutylene succinimide with number average molecular weight in the range 350 to 5000, preferably 500 to 3000.

Succinimide dispersants and their preparation are disclosed, for instance in US Patent 4,234, 435.

In one embodiment the invention further comprises at least one dispersant derived from polyisobutylene, an amine and zinc oxide to form a polyisobutylene succinimide complex with zinc. The polyisobutylene succinimide complex with zinc can be used alone or in combination with other dispersants.

Another class of ashless dispersant is Mannich bases. Mannich dispersants are the reaction products of alkyl phenols in which the alkyl group contains at least 30 carbon atoms with aldehydes (especially formaldehyde) and amines (especially polyalkylene polyamines).

Dispersants can also be post-treated conventional method by a reaction with any of a variety of agents. Among these are urea, thiourea, dimercaptothiadiazoles, carbon disulfide, aldehydes, ketones, carboxylic acids, hydrocarbon-substituted succinic anhydrides, maleic anhydride, nitriles, epoxides, boron compounds, and phosphorus compounds.

Antiwear Agents The lubricating oil composition may additionally contain an antiwear agent. Useful antiwear agents other than ZDDP include phosphoric acid esters or salt thereof ; phosphites ; and phosphorus-containing carboxylic esters, ethers, and amides or mixtures thereof.

Antioxidants Antioxidants are known materials and include diphenylamines, sterically hindered phenols, molybdenum dithiocarbamates and sulphurised olefins.

Examples of suitable diphenylamine antioxidants include octyl diphenylamine, nonyl diphenylamine, bis-octyl diphenylamine, bis-nonyl diphenylamine or mixtures thereof.

Examples of sterically hindered phenols can include 2,6-di-tert- butylphenol, 4-Methyl-2,6-di-tert-butylphenol, 4-ethyl-2,6-di-tert-butylphenol, 4-propyl-2,6-di-tert-butylphenol, 4-butyl-2, 6-di-tert-butylphenol 2,6-di-tert- butylphenol, 4-pentyl-2,6-di-tert-butylphenol, 4-hexyl-2, 6-di-tert-butylphenol, 4-heptyl-2,6-di-tert-butylphenol, 4-(2-ethylhexyl)-2, 6-di-tert-butylphenol, 4- octyl-2, 6-di-tert-butylphenol, 4-nonyl-2,6-di-tert-butylphenol, 4-decyl-2,6-di- tert-butylphenol, 4-undecyl-2, 6-di-tert-butylphenol, 4-dodecyl-2, 6-di-tert- butylphenol, 4-tridecyl-2, 6-di-tert-butylphenol, 4-tetradecyl-2,6-di-tert- butylphenol, 3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionic acid butyl ester, 3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionic acid methyl ester, 3- (3, 5-di-tert-' butyl-4-hydroxyphenyl) propionic acid 2-ethylhexyl ester and mixtures thereof.

In one embodiment the sterically hindered phenol is 2,6-di-tert- butylphenol and mixtures thereof. In one embodiment the sterically hindered phenol is 4- (2-ethylhexyl)-2, 6-di-tert-butylphenol and mixtures thereof. In one embodiment the sterically hindered phenol is 4-dodecyl-2, 6-di-tert-butylphenol and mixtures thereof.

In one embodiment two sterically hindered phenols can be linked through a bridging group typically located at position 2-or 4-relative to the hydroxyl group. The bridging group can include-CH2- (methylene bridge) or -CH20CH2- (ether bridge) or mixtures thereof. Examples of methylene-bridged sterically hindered phenols include but are not limited to 4, 4-methylenebis (6- tert-butyl-o-cresol), 4, 4-methylenebis (2-tert-amyl-o-cresol), 2, 2- methylenebis (4-methyl-6-tert-butylphenol), 4, 4-methylene-bis (2,6-di-tertbutyl- phenol) and mixtures thereof Suitable examples of molybdenum dithiocarboamates include commercial materials sold under the trade names such as Vanlube 822 and

MolyvanTM A from R. T. Vanderbilt Co. , Ltd. , and Adeka Sakura-LubeTM S-100 and S-165 and S-600 from Asahi Denka Kogyo K. K.

Examples of suitable olefins that can be sulphurised include propylene, isobutylene, pentene, hexane, heptene, octane, nonene, decene, undecene, dodecen,, undecyl, tridecene, tetradecene, pentadecene, hexadecene, heptadecene, octadecene, octadecenene, nonodecene, eicosene or mixtures thereof. In one embodiment, hexadecene, heptadecene, octadecene, octadecenene, nonodecene, eicosene or mixtures thereof and their dimers, trimers and tetramers are especially preferred olefins. Alternatively, the olefin can be a Diels-Alder adduct of a diene such as 1,3-butadiene and an unsaturated ester such as butyl (meth) acrylate.

Another class of sulphurised olefins include fatty acids and their esters.

The fatty acids are often obtained from vegetable oil or animal oil; and typically contain 4 to 22 carbon atoms. Examples of suitable fatty acids and their esters include triglycerides, oleic acid, linoleic acid, palmitoleic acid or mixtures thereof. Often, the fatty acids are obtained from lard oil, tall oil, peanut oil, soybean oil, cottonseed oil, sunflower seed oil or mixtures thereof.

In one embodiment fatty acids and mixed with olefins.

Corrosion Inhibitors Corrosion inhibitors can include amine salts of carboxylic acids such as octylamin octanoate, condensation products of dodecenyl succinic acid or anhydride and a fatty acid such as oleic acid with a polyamine, e. g. a polyalkylene polyamine such as triethylenetetramine, and half esters of alkenyl succinic acids in which the alkenyl radical contains 8 to 24 carbon atoms with alcohols such as polyglycols.

Antiscuffing Agents The lubricant may also contain an antiscuffing agent. Antiscuffing agents that decrease adhesive wear are often sulphur containing. compounds.

Typically the sulphur containing compounds include organic sulphides and polysulphides, such as benzyldisulphide, bis- (chlorobenzyl) disulphide, dibutyl tetrasulphide, di-tertiary butyl polysulphide, sulphurised sperm oil, sulphurised methyl ester of oleic acid, sulphurised alkylphenol, sulphurised dipentene,

sulphurised terpene, sulphurised Diels-Alder adducts, alkyl. sulphenyl N'N- dialkyl dithiocarbamates, the reaction product of polyamines with polybasic acid esters, chlorobutyl esters of 2,3-dibromopropoxyisobutyric acid, acetoxymethyl esters of dialkyl dithiocarbamic acid and acyloxyalkyl ethers of xanthogenic acids and mixtures thereof.

Extreme Pressure Agents Extreme Pressure (EP) agents that are soluble in the oil include sulphur and chlorosulphur-containing EP agents, chlorinated hydrocarbon EP agents, phosphorus EP agents, and mixtures thereof. Examples of such EP agents include chlorinated wax; organic sulphides and polysulphides such as benzyldisulphide, bis- (chlorobenzyl) disulphide, dibutyl tetrasulphide, sulphurised sperm oil, sulphurised methyl ester of oleic acid, sulphurised alkylphenol, sulphurised dipentene, sulphurised terpene, and sulphurised Diels- Alder adducts; phosphosulphurised hydrocarbons such as the reaction product of phosphorus sulphide with, turpentine or methyl oleate ; phosphorus esters such as the dihydrocarbon and trihydrocarbon phosphites, e. g., dibutyl phosphite, diheptyl phosphite, dicyclohexyl phosphite, pentylphenyl phosphite; dipentylphenyl phosphite, tridecyl phosphite, distearyl phosphite and polypropylene substituted phenol phosphite ; metal thiocarbamates such as zinc dioctyldithiocarbamate and barium heptylphenol diacid; the zinc salts of a phosphorodithioic acid; amine salts of alkyl and dialkylphosphoric acids, including, for example, the amine salt of the reaction product of a dialkyldithiophosphoric acid with propylene oxide; and mixtures thereof.

Foam Inhibitors Foam inhibitors are known and can include organic silicones such as polyacetates, dimethyl silicone, polysiloxanes, polyacrylates or mixtures thereof. Examples of foam inhibitors include poly ethyl acrylate, poly 2- ethylhexylacrylate and poly vinyl acetate.

Demulsifiers Demulsifiers are known and include derivatives of propylene oxide, ethylene oxide, polyoxyalkylene alcohols, alkyl amines, amino alcohols, diamines and polyamines reacted sequentially with ethylene oxide or

substituted ethylene oxides. Examples of demulsifiers include trialkyl phosphates, polyethylene glycols, polyethylene oxides, polypropylene oxides and (ethylene oxide-propylene oxide) polymers.

Pour Point Depressants Pour point depressants are known and include esters of maleic anhydride-styrene copolymers, polymethacrylates ; polyacrylates; polyacrylamides; condensation products of haloparaffin waxes and aromatic compounds; vinyl carboxylate polymers; and terpolymers of dialkylfumarates, vinyl esters of fatty acids, ethylene-vinyl acetate copolymers, alkyl phenol formaldehyde condensation resins, alkyl vinyl ethers and mixtures thereof.

Friction Modifiers Friction modifiers other than a borate ester are known and can include fatty amines, esters, especially glycerol esters such as glycerol monooleate, fatty phosphites, fatty acid amides, fatty epoxides, alkoxylated fatty amines, metal salts of fatty acids, sulfurized olefins, fatty imidazolines, condensation products of carboxylic acids and polyalkylene-polyamines, amine salts of alkylphosphoric acids.

Viscosity Modifiers Viscosity modifiers are known and are typically polymeric materials including styrene-butadiene rubbers, ethylene-propylene copolymers, polyisobutenes, hydrogenated styrene-isoprene polymers, hydrogenated radical isoprene polymers, polymethacrylate acid esters, polyacrylate acid esters, polyalkyl styrenes, alkenyl aryl conjugated diene copolymers, polyolefins, polyalkylmethacrylates, esters of maleic anhydride-styrene copolymers and mixtures thereof.

Some polymers can also be described as dispersant viscosity modifiers (often referred to as DVM) because they also exhibit dispersant properties.

Typically polymers of this type include polyolefins, for example, ethylene- propylene copolymers that have been functionalized with the reaction product of maleic anhydride and an amine. Another type of polymer is a polymethacrylate functionalised with an amine.

Seal Swelling Agents Seal swelling agents are known and are typically esters or low viscosity mineral oils with high naphthenic or aromatic content. Esters can be derived from monobasic and dibasic acids with monoalcohols, or esters of polyols with monobasic esters. Typically the alcohols contain 8 to 13 carbon atoms.

Suitable examples of mineral oil seal swelling agents include adipates, azelates, and sebacates. Examples of suitable mineral oil seal swell agents include Exxon Necton-37 (FN 1380) and Exxon Mineral Seal Oil (FN 3200).

Fluidity Modifiers Fluidity modifier are known and can include Hydrocal-38 which is a product identified as a refined naphthenic oil, 40 Neutral naphthenic oil and a low molecular weight poly-a,-olefin (EthylfloTM 162).

Industrial Application The lubricated part of the present invention are useful in various lubricants such as greases, gear oils, industrial fluids, hydraulic fluids, transmission fluids, turbine oils, circulating oils, fuel oils and engine oils.

In one embodiment the lubricated part of the invention provides a method for lubricating an internal combustion engine, comprising supplying thereto a lubricant comprising the composition as described herein. The invention is particularly suitable for diesel fuelled engines, gasoline fuelled engines, natural gas fuelled engine or a mixed gasoline/alcohol fuelled engine.

The use of the lubricated part of the invention can impart at least one property selected from decreased wear, decreased filter plugging, decreased sludge formation, decreased phosphorus emissions, decreased sulphur emissions, decreased sulphated ash formation and mixtures thereof.

The use of the lubricated part of the invention can decrease the total sulphur content below about 0.5 wt %, preferably below about 0.3 wt %, even more preferably below about 0.2 wt% and more preferably below about 0.15 wt %.

The use of the lubricated part of the invention can decrease the total phosphorus content below about 0.1 wt %, preferably, below about 0.085 wt %,

more preferably below about 0.06 wt %, even more preferably below about 0.055 wt % and even more preferably below about 0.05 wt %.

The use of the lubricated part of the invention can decrease the sulphated ash content below about 1. 5 wt %, preferably below about 1.1 wt %, more preferably below about 1.0 wt %, even more preferably below about 0.8 wt % and even more preferably below about 0.5 wt %.

The following examples provide an illustration of the invention. These examples are non exhaustive and are not intended to limit the scope of the invention.

EXAMPLES Lubricating Oil Composition A A 15W-40 formulation is prepared containing about 15 percent of 100N API Group XX (ASK INVENTORS) base oil, about 4.05 riam 2s-' (cSt) at 100°C and about 85 percent of 100N Group XX ASK INVENTORS) base oil, about 6.5 mm2s~1 (cSt) at 100°C. Additionally, about 6.8 wt % of a viscosity modifier (olefin copolymer), about 0.75 wt % of boron containing friction modifier, about 4.0 wt % of a sterically hindered phenol of the antioxidant 3- (3, 5-Di-tert- butyl-4-hydroxyphenyl) propionic acid butyl ester, about 10 wt % of polyisobutylene dispersant, about 100 ppm of a commercially available silicone antifoam agent are added to the lubricant formulation, about 2.1 wt % of magnesium phenate detergent including diluent oil, about 0.6 wt % of calcium sulphonate detergent including diluent oil and about 0.6 wt % polyisobutylene salixarate detergent including diluent oil. The formulation is used to lubricate valve train components with no coating.

Lubricating Oil Composition B About 100g of a 15W-40 formulation is prepared containing about 5 percent of 600N API Group XX (ASK INVENTORS) base oil, about 12.2 mm 2s-1 (cSt) at 100°C and about 95 percent of 100N Group XX ASK INVENTORS) base oil, about 6.5 mm 2s-' (cSt) at 100°C. Additionally, about 6.8 wt % of a viscosity modifier (olefin copolymer), about 0.2 wt % of maleic anhydride styrene copolymer viscosity index improver, about 1.3 wt % of boron containing friction modifier, about 4. 0 wt % of a sterically hindered phenol

antioxidant 3- (3, 5-Di-tert-butyl-4-hydroxyphenyl) propionic acid butyl ester, about 10 wt % of polyisobutylene dispersant, about 100 ppm of a commercially available silicone antifoam agent are added to the lubricant formulation, about 2.1 wt % of magnesium phenate detergent including diluent oil, about 1. 04 wt % of calcium dodecyl phenate sulphide detergent and about 0.6 wt % of calcium sulphonate detergent including diluent oil. The formulation is used to lubricate valve train components with no coating.

Reference Example M A lubricating oil composition A and used to lubricate valve train components without a coating.

Reference Example N A lubricating oil composition B and used to lubricate valve train components without a coating.- Example 1 An oil of lubricating viscosity is prepared using the formulation of "Lubricating Oil Composition A"and used to lubricate valve train components coated with a commercially available chromium nitride coating (Balinit@D) from Balzers Limited.

Example 2 An oil of lubricating viscosity is prepared using the formulation of "Lubricating Oil Composition A"and used to lubricate the rocker arm is coated with a commercially available tungsten carbide coating (Balinit) C) from Balzers Limited.

Example 3 An oil of lubricating viscosity is prepared using the formulation of "Lubricating Oil Composition B"and used to lubricate the rocker arm is coated with a commercially available chromium nitride coating (BalinitOD) from Balzers Limited.

Example 4 An oil of lubricating viscosity is prepared using the formulation of "Lubricating Oil Composition B"and used to lubricate valve train components

coated with a commercially available tungsten carbide coating (Balinit (g) C) from Balzers Limited.

Test 1 Cummins Ml 1 Wear Test Reference Examples 1 and 2 as well as Examples 1 to 4 are run in the API CH-4 Cummins Ml 1 Engine test. This test uses a Cummins 370-E block engine, which is an electronically governed in-line 6-cylinder 4-stroke, compression ignition engine. The test is conducted in two stages, the first about 65 hours and the second about 20 hours. During the first stage, the engine is over-fuelled and operated with retarded timing to generate soot at an accelerated rate. During the second stage the engine is run at lower speed and higher torque, to induce wear. The crosshead wear, considered to be representative of valve train wear, is determined and averaged for 12 crossheads. The valve adjuster wear is averaged for 12 adjusters. Injector adjuster wear is averaged over six adjusters. Generally lower weight loss indicates better wear performance The results obtained are: Example Valve Adjuster weight Injector Adjuster weight loss (mg) loss (mg) Example Reference M 4.1 41.4 Example 1 7. 3 39. 3 Example 2 4. 9 19. 8 Example Reference N 13.5 42.6 Example 3 4. 1 38. 1 Example 4 3. S 36. 1 Test 2 Sludge Test The amount of sludge produced is measured by placing oil of lubricating viscosity in an oil pan and rocker cover and left to stand for about 6 hours at about 24°C. The sample is then placed at an angle of about 60° from horizontal for about 8 hours at about 24°C. The amount of sludge on the oil pan and rocker cover is in general those deposits that do not drain off, but which can be removed by wiping. The grading scheme rates the deposits on the oil pan and rocker cover between 1 and 10, with 10 being completely free of sludge. The results obtained are: Example Sludge Rating Example Reference M 7.5 Example 1 7.7 Example 2 7.3 Example Reference N 6. 8 Example 3 7. 1 Example 4 7. 3

Test 3 Filter Plugging The test is carried out on the API CH-4 Cummins Ml 1 Engine test and the Cummins 370-E block engine. The test measures the difference in pressure between air leaving a filter at the start and end of the test. Generally the better results are obtained for examples with low differences in filter pressure. The results obtained are: Example Difference in Filter Pressure (kPa) Example Reference M 25. 3 Example 1 31.6 Example 2 101. 1 Example Reference N 74.8 Example 3 86. 3 Example 4 13. 6 Overall the examples indicate that the lubricating. oils used in combination with a partial hard surface coating is capable of providing at least one property selected from decreased wear, decreased filter plugging, decreased

sludge formation, decreased phosphorus emissions, decreased sulphur emissions, decreased sulphated ash formation and mixtures thereof.

While the invention has been explained, it is to be understood that various modifications thereof will become apparent to those skilled in the art upon reading the specification. Therefore, it is to be understood that the invention disclosed herein is intended to cover such modifications as fall within the scope of the appended claims.