U. S. Patent Specification No. 4,734, 209 discloses metal deactivators for functional fluids.

U. S. Patent Specification No. 4, 491, 527discloses compositions useful for the inhibition of lead paint deposition in lubricants.

Engine oil specifications are becoming more stringent in the way of performance require- ments, and new formulations are under development to meet these new specifications. En- gine oil specifications are defined in ASTM D 4485.

The new engine oil formulations under development comprise certain additive chemistries.

Many of these additive chemistries are corrosive to lead. It is difficult for formulators to meet the present engine oil specifications by employing certain beneficial additives while also meeting the specification for lead corrosion.

From 1994 onward, all diesel oils have been required to meet a lead corrosion specification defined in ASTM D 4485 and as measured according to either ASTM D 5968 (run at 125°C) or ASTM D 6594 (run at 135°C). The ASTM D 4485 Standard Specification for Performance of Engine Oils indicates a maximum allowed lead corrosion level of 60 ppm for API catego- ries CF-4 and CG-4 by ASTM D 5968 and 120 ppm for category CH-4 by ASTM D 6594.

For example, certain components of formulated engine oils that cause lead corrosion include certain detergents, antiwear additives, friction modifiers and antioxidants. Many such desired additive chemistries are disqualified from use due to causing engine oil formulations to not meet industry specifications for limits on lead corrosion.

For example, desired additive chemistries that are aggressive towards lead and are other- wise disqualified from use in engine oils include sulfur-containing additives and certain vegetable oil-derived friction modifiers.

It has surprisingly been found that formulated engine oils that comprise certain 1,2, 4-triazole metal deactivators are especially non-aggressive towards lead, for example lead engine parts such as bearings. The engine oils according to this invention meet corrosion protection performance requirements of diesel lubricant specifications defined in ASTM D 4485.

This issue of lead corrosion is generally not a problem in other types of lubricants, for exam- ple turbine and hydraulic oils.

The engine oils of this invention are diesel and universal oils. Universal oils encompass both diesel oils and passenger car oils. The engine oils are employed in internal combustion en- gines, for example, in motor vehicles fitted, for example, with engines of the Otto, Diesel, two-stroke, Wankel or orbital type.

Specifically, the present invention relates to an engine oil composition that is non-aggressive towards lead, which composition comprises (a) A base fluid, (b) At least one compound of the formula (I) (c) At least one oil additive that is aggressive towards lead and which is selected from the group consisting of antioxidants, antiwear additives, dispersants, detergents, an- tifoam additives, viscosity index improvers, copper passivators, rust inhibitors, pour- point depressants, demulsifiers and friction modifiers, where R1 and R2 are the same or different and are C1-C20alkyl, C3-C20alkenyl, C5- Cl2cycloalkyl, C7-Cl3aralkyl or C6-Cioaryl, or R1 and R2, together with the nitrogen atom to which they are each attached may form a 5-, 6-or 7-membered heterocyclic residue, or R1 and R2 are a group of formula R3X [ (-R4-) Oln (-R4)- where XisO, SorN, R3 is hydrogen or Ct-C20alkyl, R4 is Ci-Ci2alkylene, n is 0 or an integer from 1 to 6, or one of R1 and R2 is a group of formula or R2 is a group of formula (II) and Pi is a group of formula

- [R4]n-N(R5)-A-[N(R)2]m where m is 0 or 1 and, when m is zero, A is a group of formula (II) and, when m is 1, A is al- kylene or C6-Cioarylene and R5 is a group of formula (II), and where in the absence of component (b), the engine oil composition exceeds about 100 ppm lead as measured according to test ASTM D 6594.

R4 is, for example, a C-C6alkylene group, for example, a C2-C3alkylene.

The number n is for example, 0,1, 2,3, 4,5 or 6.

Alkyl is straight or branched chain and is, for example, methyl, ethyl, n-propyl, iso-propyl, n- butyl, sec-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, 2-ethylhexyl, n-nonyl, n-decyl, n-dodecyl, n-tetradecyl, n-hexadecyl, n-octadecyl or n-icosyl.

Alkenyl is straight or branched chain and is, for example, prop-2-enyl, but-2-enyl, 2-methyl- prop-2-enyl, pent-2-enyl, hexa-2, 4-dienyl, dec-10-enyl or eicos-2-enyl.

Cycloalkyl is, for example, cyclopentyl, cyclohexyl, cyclooctyl, cyclodecyl, adamantyl or cyclododecyl.

Aralkyl is, for example, benzyl, 2-phenylethyl, benzhydryl or naphthylmethyl.

Aryl is, for example, phenyl or naphthyl.

When Ri and R2 together with the nitrogen atom to which they are attached form a hetero- cyclic group, the heterocyclic group is, for example, a morpholine, pyrrolidine, piperidine or a perhydroazepine ring.

Alkylen includes, for example, methylene, ethylene, 1: 2- or 1: 3-propylene, 1: 4-butylene, 1: 6- hexylen, 1: 8-octylene, 1 : 10-decylene and 1: 12-dodecylene.

Arylene includes, for example, phenylen and naphthylene.

Specific compounds of present formula (I) include : 1-(or 4)-(dimethylaminomethyl) triazole ; 1- (or 4)- (diethylaminomethyl) triazole ; 1- (or 4)- (di-iso- propylaminomethyl) triazole ; 1- (or 4)- (di-n-butylaminomethyi) triazole ; 1- (or 4)- (di-n-hexylami- nomethyl) triazole ; 1- (or 4)- (di-isooctylaminomethyl) triazole ; 1- (or 4)- (di- (2-ethylhexyl) amino- methyl) triazole ; 1- (or 4)- (di-n-octylaminomethyl) triazole ; 1-(or 4)-(di-n-decylaminomethyl)- triazole ; 1- (or 4)- (di-n-dodecylaminomethyl) triazole ; 1- (or 4)- (di-n-octadecylaminomethyl) tri- azole ; 1- (or 4)- (di-n-eicosylaminomethyl) triazole ; 1- (or 4)-[di-(prop-2'-enyl)aminomethyl] tri-

azole ; 1-(or 4)-[di-(but-2'-enyl)aminomethyl]triazole ; 1- (or 4)-[di-(cicos-2'-enyl)aminomethyl]- triazole ; 1- (or 4)- (di-cyclohexylaminomethyl) triazole ; 1- (or 4)- (di-benzylaminomethyl) triazole ; 1- (or 4)- (di-phenylaminomethyl) triazole ; 1- (or 4)- (4'-morpholinomethyl) triazole ; 1- (or 4)- (1'- pyrrolidinomethyl) triazole ; 1- (or 4)- (1'-piperidinomethyl) triazole ; 1- (or 4)- (1'-perhydoroazep- inomethyl) triazole ; 1- (or 4)- (2', 2"-dihydroxyethyl) aminomethyl] triazole ; 1- (or 4)- (dibutoxyprop- ylaminomethyl) triazole ; 1-(or 4)-(dibutylthiopropyl-aminomethyl)triazole ; 1- (or 4)- (di-butylami- nopropyl-aminomethyl) triazole ; N, N-bis- (1- or 4-triazolylmethyl) laurylamine ; N, N-bis- (1- or 4- triazolylmethyl) oleylamine ; N, N-bis- (1- or 4-triazolylmethyl) ethanolamine and N, N, N', N'-tetra- (1-or 4-triazolylmethyl) ethylene diamine.

A representative compound of formula (I) is, for example, 1- (di-isooctylaminomethyl) triazole, that is 1-(di-isooctylaminomethyl)-1, 2, 4-triazole, or is 1-(di-(2-ethylhexyl) aminomethyl) 1,2, 4- triazole.

The present compounds of formula (I) are prepared by known methods, for example, as dis- closed in U. S. Patent Specification No. 4, 734, 209, the disclosure of which is hereby incorpo- rated by reference.

The base fluids in accordance with the invention utilize mineral oil based fluids (API Group I, II and 111), poly-a-olefins-PAOs (API Group IV), esters (API Group V), other synthetic fluids, natural oils that are animal or vegetable in origin, and mixtures thereof. The base fluids are of suitable viscosity for utilization in engine oil applications. <BR> <BR> <BR> <P>The present compounds of formula (I) are employed at concentrations of about 0.01 to about<BR> 1.0% by weight, based on the weight of the formulated engine oil. For example, the com- pounds of formula (I) are present from about 0.02 to about 0.5 weight percent; for example, from about 0.03 to about 0.3 weight percent; for example, from about 0.01 to about 0.5 or from about 0.01 to about 0.3 weight percent; for example from about 0.02 to about 1.0 or from about 0.02 to about 0.3 weight percent; for example, from about 0.03 to about 1.0 or from about 0.03 to about 0.5 weight percent.

Suitable antioxidants of component (c) are selected from: 1) Alkylated monophenols, for example 2, 6-di-tert-butyl-4-methylphenol, 2-butyl-4, 6-di- methylphenol, 2, 6-di-tert-butyl-4-ethylphenol, 2, 6-di-tert-butyl-4-n-butylphenol, 2,6-di- tert-butyl-4-iso-butylphenol, 2, 6-di-cyclopentyl-4-methylphenol, 2- (a-methyl-cyclo- hexyl)-4, 6-dimethylphenol, 2, 6-di-octadecyl-4-methylphenol, 2,4, 6-tri-cyclo-hexylphe- nol, 2, 6-di-tert-butyl-4-methoxymethylphenol, linear or side chain-branched nonylphe- nols, for example 2, 6-dinonyl-4-methylphenol, 2, 4-dimethyl-6- (1'-methyl-undec-1'-

yl) phenol, 2, 4-dimethyl-6- (1'-methylheptadec-1'-yl) phenol, 2, 4-dimethyl-6- (1'-methyl- tridec-1'-yl) phenol or mixtures thereof 2) Alkylthiomethylphenols, for example 2, 4-di-octylthiomethyl-6-tert-butylphenol, 2,4-di- octylthiomethyl-6-methylphenol, 2, 4-di-octylthiomethyl-6-ethylphenol or 2,6-di-dode- cylthiomethyl-4-nonylphenol 3) Hydroquinones and alkylated hydroquinones, for example 2, 6-di-tert-butyl-4-methoxy- phenol, 2, 5-di-tert-butylhydroquinone, 2, 5-di-tert-amylhydroquinone, 2, 6-diphenyl-4- octadecyloxyphenol, 2, 6-di-tert-butyl-hydroquinone, 2, 5-di-tert-butyl-4-hydroxyanisole, 3, 5-di-tert-butyl-4-hydroxyanisole, 3, 5-di-tert-butyl-4-hydroxyphenyl stearate or bis (3, 5-di-tert-butyl-4-hydroxyphenyl) adipate 4) tocopherols, for example a-, p-, y-or 8-tocopherol or mixtures thereof (vitamin E) 5) Hydroxylated thiodiphenyl ethers, for example 2, 2'-thiobis (6-tert-butyl-4-methylphe- nol), 2,2'-thiobis (4-octylphenol), 4, 4'-thiobis (6-tert-butyl-3-methylphenol), 4,4'-thiobis- (6-tert-butyl-2-methylphenol), 4,4'-thiobis (3, 6-di-sec.-amylphenol) or 4,4'-bis (2,6-di- methyl-4-hydroxyphenyl) disulfide 6) Alkylidenebisphenols, for example 2, 2'-methylenebis (6-tert-butyl-4-methylphenol), 2, 2'-methylenebis (6-tert-butyl-4-ethylphenol), 2, 2'-methylenebis (4-methyl-6- (a-methyl- cyclohexyl)-phenol), 2, 2'-methylenebis (4-methyl-6-cyclohexylphenol), 2, 2'-methylene- bis (6-nonyl-4-methylphenol), 2, 2'-methylenebis (4, 6-di-tert-butylphenol), 2, 2'-ethyl- denebis (4, 6-di-tert-butylphenol), 2, 2'-ethylidenebis (6-tert-butyl-4-isobutylphenol), 2,2'- methylenebis (6- (a-methylbenzyl)-4-nonylphenol), 2, 2'-methylene-bis (6- (a, a-dimethyl- benzyl)-4-nonylphenol), 4, 4'-methylenebis (2, 6-di-tert-butylphenol), 4, 4'-methylene- bis (6-tert-butyl-2-methylphenol), 1,1-bis (5-tert-butyl-4-hydroxy-2-methylphenyl)- butane, 2,6-bis (3-tert-butyl-5-methyl-2-hydroxybenzyl)-4-methylphenol, 1,1, 3-tris (5- tert-butyl-4-hydroxy-2-methylphenyl) butane, 1,1-bis (5-tert-butyl-4-hydroxy-2-methyl- phenyl)-3-n-dodecylmercaptobutane, ethylene glycol bis (3,3-bis (3'-tert-butyl-4'- hydroxyphenyl) butyrate), bis (3-tert-butyl-4-hydroxy-5-methylphenyl) dicyclo-penta- diene, bis (2- (3'-tert-butyl-2'-hydroxy-5'-methylbenzyl)-6-tert-butyl-4-me thylphen yl) terephthalate, 1,1-bis (3, 5-dimethyl-2-hydroxyphenyl) butane, 2,2-bis (3,5-di-tert-bu- tyl-4-hydroxyphenyl) propane, 2,2-bis (5-tert-butyl-4-hydroxy-2-methylphenyl)-4-n-do- decylmercaptobutane or 1,1, 5,5-tetra (5-tert-butyl-4-hydroxy-2-methylphenyl)-pentane 7) 0-N-and S-benzyl compounds, for example 3,5, 3', 5'-tetra-tert-butyl-4, 4'-dihydroxy- dibenzyl ether, octadecyl 4-hydroxy-3, 5-dimethylbenzylmercaptoacetate, tridecyl 4- hydroxy-3, 5-di-tert-butylbenzylmercaptoacetate, tris (3, 5-di-tert-butyl) amine, bis (4-tert-

butyl-3-hydroxy-2, 6-dimethylbenzyl) dithioterephthalate, bis (3, 5-di-tert-butyl-4-hy- droxybenzyl) sulfide or isooctyl 3, 5-di-tert-butyl-4-hydroxy-benzylmercaptoacetate 8) Hydroxybenzylated malonates, for example dioctadecyl 2,2-bis (3, 5-di-tert-butyl-2-hy- droxybenzyl) malonate, dioctadecyl 2- (3-tert-butyl-4-hydroxy-5-methylbenzyl)-malo- nate, d-dodecyl mercaptoethyl-2, 2-bis (3, 5-di-tert-butyl-4-hydroxybenzyl)-malonate or di (4- (1, 1,3, 3-tetramethylbutyl) phenyl)-2, 2-bis (3, 5-di-tert-butyl-4-hydroxyben- zyl) malonate 9) Aromatic hydroxybenzyl compounds, for example 1,3, 5-tris (3, 5-di-tert-butyl-4- hydroxybenzyl)-2, 4, 6-trimethylbenzene, 1,4-bis (3, 5-di-tert-butyl-4-hydroxybenzyl)- 2,3, 5, 6-tetramethylbenzene or 2, 4,6-tris (3, 5-di-tert-butyl-4-hydroxybenzyl) phenol 10) Triazine compounds, for example 2, 4-bisoctylmercapto-6- (3, 5-di-tert-butyl-4- hydroxyanilino)-1, 3,5-triazine, 2-octylmercapto-4, 6-bis (3, 5-di-tert-butyl-4-hydroxyani- lino)-1, 3,5-triazine, 2-octylmercapto-4, 6-bis (3, 5-di-tert-butyl-4-hydroxyphenoxy)-1, 3,5- triazine, 2,4, 6-tris (3, 5-di-tert-butyl-4-hydroxyphenoxy)-1, 2,3-triazine, 1,3, 5-tris (3,5-di- tert-butyl-4-hydroxybenzyl)-isocyanurate, 1,3, 5-tris (4-tert-butyl-3-hydroxy-2, 6- dimethylbenzyl) isocyanurate, 2,4, 6-tris (3, 5-di-tert-butyl-4-hydroxyphenylethyl)-1, 3,5- triazine, 1,3, 5-tris (3, 5-di-tert-butyl-4-hydroxyphenylpropionyl) hexahydro-1,3, 5-triazine or 1,3, 5-tris (3, 5-dicyclohexyl-4-hydroxybenzyl)-isocyanurate 11) Benzylphosphonates, for example dimethyl 2, 5-di-tert-butyl-4-hydroxybenzyl- phosphonate, diethyl 3, 5-di-tert-butyl-4-hydroxybenzylphosphonate, dioctadecyl 3,5- di-tert-butyl-4-hydroxybenzylphosphonate, dioctadecyl 5-tert-butyl-4-hydroxy-3-me- thylbenzylphosphonate or the calcium salt of the monoethyl ester of 3, 5-di-tert-butyl- 4-hydroxybenzylphosphonic acid 12) Acylaminophenols, for example 4-hydroxylauranilide, 4-hydroxystearanilide or octyl N- (3, 5-di-tert-butyl-4-hydroxyphenyl) carbamate 13) Esters of ß-(3, 5-di-tert-butyl-4-hydroxyphenyl) propionic acid, p- (5-tert-buty)-4-hydroxy- 3-methylphenyl) propionic acid, ß-(3, 5-dicyclohexyl-4-hydroxyphenyl)-propionic acid, 3, 5-di-tert-butyl-4-hydroxyphenylacetic acid or p- (5-tert-buty)-4-hydroxypheny))-3- thiabutyric acid with mono-or polyhydric alcohols, e. g. with methanol, ethanol, n-oc- tanol, i-octanol, octadecanol, 1, 6-hexanediol, 1, 9-nonanediol, ethylene glycol, 1,2- propanediol, neopentyl glycol, thiodiethylene glycol, diethylene glycol, triethylene gly- col, pentaerythritol, tris (hydroxyethyl) isocyanurate, N, N'-bis (hydroxyethyl) oxalamide, 3-thiaundecanol, 3-thiapentadecanol, trimethyl-hexanediol, trimethylolpropane, 4-hy- droxymethyl-1-phospha-2, 6, 7-trioxabicyclo (2.2. 2) octane, glycerol or transesterifica-

tion products based on natural triglycerides of, for example, coconut oil, rape seed oil, sunflower oil or colza oil 14) Amides of ß-(3, 5-di-tert-butyl-4-hydroxyphenyl) propionic acid, e. g. N, N'-bis (3,5-di-tert- butyl-4-hydroxyphenylpropionyl) hexamethylenediamine, N, N'-bis (3, 5-di-tert-butyl-4- hydroxyphenylpropionyl) trimethylenediamine or N, N'-bis (3, 5-di-tert-butyl-4-hydroxy- phenylpropionyl) hydrazine 15) Ascorbic acid (vitamin C) 16) Amine-type antioxidants, for example N, N'-diisopropyl-p-phenylenediamine, N, N'-di- sec-butyl-p-phenylenediamine, N, N'-bis (1, 4-dimethylpentyl)-p-phenylenediamine, N, N'-bis (1-ethyl-3-methyl-pentyl)-p-phenylenediamine, N, N'-bis (1-methyl-heptyl)-p- phenylendiamine, N, N'-dicyclohexyl-p-phenylenediamine, N, N'-diphenyl-p-phenylene- diamine, N, N'-di- (naphth-2-yl)-p-phenylenediamine, N-isopropyl-N'-phenyl-p-phenyl- enediamine, N- (1, 3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, N- (l-methylhep- tyl) N'-phenyl-p-phenylenediamine, N-cyclohexyl-N'-phenyl-p-phenylenediamine, 4-(p- toluenesulfonamido) diphenylamine, N, N'-dimethyl-N, N'-di-sec-butyl-p-phenylenedi- amine, diphenylamine, N-allyldiphenylamine, 4-isopropoxy-diphenylamine, N-phenyl- 1-naphthylamine, N- (4-tert-octylphenyl)-1-naphthylamine, N-phenyl-2-naphthylamine, octylated diphenylamine, e. g. p, p'-di-tert-octyidiphenyl-amine, 4-n-butylaminophenol, 4-butyrylaminophenol, 4-nonanoylaminophenol, 4-dodecanoylaminophenol, 4-octa- decanoylaminophenol, di- (4-methoxyphenyl)-amine, 2, 6-di-tert-butyl-4-dimethyl- amino-methyl-phenol, 2, 4'-diamino-diphenylmethane, 4, 4'-diamino-diphenylmethane, N, N, N', N'-tetramethyl-4, 4'-diamino-diphenylmethane, 1, 2-di-((2-methyl-phenyl)-ami- no) -ethane, 1, 2-di- (phenylamino) propane, (o-tolyl) biguanide, di (4- (1', 3'-dimethyl-but- yl)-phenyl) amine, tert-octylated N-phenyl-1-naphthylamine, a mixture of mono-and dialkylated tert-butyl/tert-octyldiphenylamines, a mixture of mono-and dialkylated nonyidiphenylamines, a mixture of mono-and dialkylated dodecyidiphenylamines, a mixture of mono-and dialkylated isopropyl/isohexyldiphenylamines, mixtures of mono-and dialkylated tert-butyidiphenylamines, 2,3-dihydro-3, 3-dimethyl-4H-1, 4- benzothiazine, phenothiazine, a mixture of mono-and dialkylated tert-butyl/tert-octyl- phenothiazines, a mixture of mono-and dialkylated tert-octyl-phenothiazines, N- allylphenothiazine, N, N, N', N'-tetraphenyl-1, 4-diaminobut-2-ene, N, N-bis- (2, 2,6, 6- tetramethylpiperidin-4-yl) hexamethylenediamine, bis-(2, 2,6, 6-tetramethylpiperidin-4- yl) sebacate, 2,2, 6, 6-tetramethylpiperidin-4-one or 2,2, 6, 6-tetramethylpiperidin-4-ol and

17) Aliphatic or aromatic phosphites, esters of thiodipropionic acid or of thiodiacetic acid, or salts of dithiocarbamic or dithiophosphoric acid, 2,2, 12, 12-tetramethyl-5, 9-dihy- droxy-3,7, 1-trithiatridecane or 2, 2,15, 15-tetramethyl-5, 12-dihydroxy-3,7, 10,14-tetra- thiahexadecane.

Suitable antiwear additives of component (c) are selected from: 1) Dihydrocarbyl dithiophosphate metal salts where the metal is aluminum, lead, tin manganese, cobalt, nickel, zinc or copper, but most often zinc. The zinc salt (zinc dialkyl dithiophosphate) is represented as where R and R'are independently represent C-C20alkyl, C3-C20alkenyl, C5-C 2cyclo- alkyl, C7-Cl3aralkyl or C6-Cioaryl, for example R and R'are independently Cl-C, 2alkyl and 2) Sulfur-and/or phosphorus-and/or halogen-containing compounds, such as sulfurized olefins and vegetable oils, tritolyl phosphate, tricresyl phosphate, chlorinated paraf- fins, alkyl and aryl di-and trisulfides, amine salts of mono-and dialkyl phosphates, amine salts of methylphosphonic acid, diethanolaminomethyltolyltriazole, di (2-ethyl- hexyl)-aminomethyltolyltriazole, derivatives of 2, 5-dimercapto-1,3, 4-thiadiazole, ethyl ((bisisopropyloxyphosphinothioyl) thio) propionate, triphenyl thiophosphate (triphenyl phosphorothioate), tris (alkylphenyl) phosphorothioates and mixtures thereof (for ex- ample tris (isononylphenyl) phosphorothioate), diphenylmonononylphenyl phosphoro- thioate, isobutylphenyl diphenyl phosphorothioate, the dodecylamine salt of 3-hydro- xy-1,3-thiaphosphetan 3-oxide, trithiophosphoric acid 5,5, 5-tris (isooctyl 2-acetate), derivatives of 2-mercaptobenzothiazole, such as 1- (N, N-bis (2-ethylhexyl) amino- methyl)-2-mercapto-1 H-1, 3-benzothiazole or ethoxycarbonyl 5-octyldithiocarbamate.

Suitable dispersants of component (c) are selected from: 1) Mannich bases that are condensation reaction products of a high molecular weight phenol, an alkylen polyamine and an aldehyde such as formaldehyde 2) Succinic-based dispersants that are reaction products of a olefin polymer and suc- cinic acylating agent (acid, anhydride, ester or halide) further reacted with an organic hydroxy compound and/or an amine and

3) High molecular weight amides and esters such as reaction products of a hydrocarbyl acylating agent and a polyhydric aliphatic alcohol (such as glycerol, pentaerythritol or sorbitol).

Ashless (metal-free) polymeric materials that usually contain an oil soluble high molecular weight backbone linked to a polar functional group that associates with particles to be dis- persed are typically used as dispersants. Commonly used hydrocarbon backbone materials are olefin polymers and copolymers, i. e.-ethylene, propylene, butylene, isobutylene, styrene; there may or may not be further functional groups incorporated into the backbone of the polymer. Polar materials such as amines, alcohols, amides or esters are attached to the backbone via a bridge.

Suitable detergents of component (c) are selected from: calcium, magnesium, barium, so- dium or lithium salts of organic acids, for example sulphonates, alkylphenates, sulfurised al- kyl phenates, carboxylates, salicylates, phosphonates, thiophosphonates and phosphinates.

The salts may be neutral or may be overbased by, for example, metal hydroxides or carbon- ates.

Suitable antifoam additives of component (c) are selected from: silicone oils, polysiloxanes and polyethylene glycol ethers.

Suitable viscosity index improvers of component (c) are selected from: polyisobutylene, co- polymers of ethylene and propylene, polyacrylates, polymethacrylates, vinylpyrrolidone/ methacrylate copolymers, polyvinylpyrrolidones, polybutenes, olefin copolymers, styrene/ acrylate copolymers, styrene/isoprene copolymers, styrene/isobutadiene copolymers, isoprene/butadiene copolymers and polyethers.

Suitable copper passivators of component (c) are selected from: 1) Benzotriazoles and their derivatives, for example 4-or 5-alkylbenzotriazoles (e. g. tolutriazole) and derivatives thereof, 4,5, 6, 7-tetrahydrobenzotriazole, 5, 5'-methylene- bisbenzotriazole ; Mannich bases of benzotriazole or tolutriazole, such as 1- (di (2- ethylhexyl) aminomethyl) tolutriazole and 1- (di- (2-ethylhexyl) aminomethyl)-benzotria- zole ; alkoxyalkylbenzotriazoles, such as 1- (nonyloxymethyl)-benzotriazole, 1- (1-bu- toxyethyl)-benzotriazole or 1- (1-cyclohexyloxybutyl)-tolutriazole 2) Imidazole derivatives, for example 4, 4'-methylenebis (2-undecyl-5-methyl-imidazole), bis ((N-methyl) imidazol-2-yl) carbinol octyl ether

3) Sulfur-containing heterocyclic compounds, for example 2-mercaptobenzothiazole, 2,5-dimercapto-1, 3, 4-thiadiazole, 2, 5-dimercaptobenzothiadiazole and derivatives thereof or 3,5-bis (di (2-ethylhexyl) aminomethyl)-1, 3, 4-thiadiazolin-2-one, and 4) Amino compounds, for example salicylidenepropylenediamine, salicylaminoguanidine or salts thereof.

Suitable rust inhibitors of component (c) are selected from: 1) Nonionic polyoxyalkylene polyols and their esters, polyoxyalkylene phenols, organic acids, their esters, metal salts, amine salts and anhydrides, for example alkyl-and al- kenylsuccinic acids and the partial esters thereof with alcohols, diols or hydroxycar- boxylic acids, partial amides of alkyl-and alkenyisuccinic acids, 4-nonylphenoxyacetic acid, alkoxy-and alkoxyethoxycarboxylic acids, such as dodecyloxyacetic acid, dode- cyloxy (ethoxy) acetic acid and the amine salts thereof, or N-oleoylsarcosine, sorbitan monooleate, lead naphthenate and alkenylsuccinic anhydrides, for example dode- cenylsuccinic anhydride, 2-(2-carboxyethyl)-1-dodecyl-3-methylglycerol and its salts, for example, sodium and triethanolamine salts 2) Nitrogen-containing compounds selected from: i) Primary, secondary or tertiary aliphatic or cycloaliphatic amines and amine salts of organic and inorganic acids, for example oil-soluble alkylammonium carboxylates, and also 1- (N, N-bis (2-hydroxyethyl) amino)-3- (4-nonylphenoxy) propan-2-ol, or ii) Heterocyclic compounds, for example: substituted imidazolines or oxazolines, for example, 2-heptadecenyl-1-(2-hydroxyethyl)-imidazoline 3) Phosphorus-containing compounds, for example amine salts of phosphoric acid, phosphoric acid partial esters or phosphonic acid partial esters or zinc dialkyldithio- phosphates 4) Sulfur-containing compounds, for example barium dinonylnaphthalene-sulfonates, calcium petroleumsulfonates, alkylthio-substituted aliphatic carboxylic acids, esters of aliphatic 2-sulfocarboxylic acids or salts thereof, and 5) Glycerol derivatives, for example glycerol monooleate, 1- (alkylphenoxy)-3- (2-hy- droxyethyl) glycerols, 1- (alkylphenoxy)-3- (2, 3-dihydroxypropyl) glycerols or 2-car- boxyalkyl-1, 3-dialkylglycerols.

Suitable pour point depressants of component (c) are selected from polymethacrylates and alkylated naphthalene derivatives.

Suitable demulsifiers of component (c) are selected from polyetherpolyols and dinonyinaph- thalenesulfonates.

Suitable friction modifiers of component (c) are selected from fatty acids and their deriva- tives, e. g. natural esters of fatty acids such as glycerol monooleate, amides, imides and amines, e. g. oleylamine, sulfur containing organomolybdenum dithiocarbamates, sulfur- phosphorus containing organomolybdenum dithiophosphates, sulfur-nitrogen containing or- ganomolybdenum compounds based on dispersants, molybdenum carboxylate salts, molyb- denum-amine complexes, molybdenum amine/alcohol/amid complexes and molybdenum cluster compounds, Teflon@ and molybdenum disulfide.

Additives that are aggressive towards lead are antioxidants, antiwear additives, detergents, copper passivators or friction modifiers, such as sulfur-containing antioxidants, sulfur-con- taining antiwear additives, sulfur-containing copper passivators or vegetable oil-derived fric- tion modifiers. For example, the sulfur-containing antioxidants aggressive towards lead are phenothiazine antioxidants.

The additives of component (c) are added in the customary amounts in each case in the range from about 0.01 to about 10.0% by weight, based on the engine oil composition.

The compounds of the formula (I) can be introduced into the engine oil in manners known per se. The compounds are readily soluble in oils. It is also possible to prepare a so-called additive master batch (package) that can be diluted with the corresponding fluid to use con- centrations at the rate at which they are required. The compounds of formula (I) may be in- troduced as part of an additive package.

In the absence of the present compounds of formula (I), the engine oils comprising compo- nents (a) and (c) do not meet or only come close to meeting the lead corrosion specification defined in ASTM D 4485 as measured by ASTM D 6594. That is, the engine oils comprising components (a) and (c), in the absence of the present compounds of formula (I), have in ex- cess of about 100 ppm, about 120 ppm, about 150 ppm, about 180 ppm, or about 210 ppm as measured by ASTM D 6594.

The invention also relates to a method of preventing corrosion of lead parts that are in the presence of an engine oil composition comprising (a) a base fluid and (c) at least one oil additive that is aggressive towards lead and which is selected from the group consisting of antioxidants, antiwear additives, dispersants, detergents, antifoam additives, viscosity index improvers, copper passivators, rust inhibitors, pourpoint depressants, demulsifiers and friction modifiers, which method comprises incorporating into said engine oil composition (b)

at least one compound of the formula (I), where in the absence of component (b), the engine oil composition exceeds about 100 ppm lead as measured according to test ASTM D 6594.

The following Example illustrates the invention in more detail. They are not to be construed as limiting the instant invention in any manner whatsoever.

Example ASTM D 6594 Evaluation of Corrosiveness of Diesel Engine Oil at 135°C In this test four metal specimen of copper, lead, tin and phosphor bronze are immersed in a measured amount of engine oil. The oil, at 135°C is blown with air for 168 hours. When the test is completed, the stressed oil is examined to detect corrosion and corrosion products.

The presence of copper, lead and tin in the used oil is measured by ICP. A result of less than 50 ppm lead in the stressed oil is desirable.

A fully formulated, non-corrosive engine oil is used as the base formulation for this example.

To demonstrate the effectiveness of the invention, 1.0 weight percent of a friction modi- fier/corrosion inhibitor, glycerol monooleate (GMO) and 0.5 weight percent of a sulfur-con- taining anti wear/extreme pressure additive, diternonyltrisulfide (TPSe 27), are added sepa- rately to the base formulation. These are both tested per ASTM D 6594 with and without 0.2 weight percent of a compound of formula (1): 1-(di-(2-ethylhexyl) aminomethyl) 1,2, 4-triazole (Irgamets 30, Ciba Specialty Chem. ). The results for lead corrosion generated during the test are shown in the following Table : No IRGAMET 30 With IRGAMET 30 1) Base formulation 75 ppm----- 2) (1) plus 1. 0% GMO 358 ppm 29 ppm 3) (1) plus 0. 5% TPS 27 117 ppm 43 ppm

Both the GMO and TPS 27 add to the corrosion of the base formulation making it unsuitable for use. In each case, IRGAMET 30 reduces the corrosion significantly to very acceptable levels.