This invention relates to the use of an active fuel ingredient in known additive technologies for the purpose of achieving a technical improvement of the keep-clean performance in respect of gasoline engine inlet systems, and of optimizing the cost-to-benefit ratio of known gasoline additives.

The use of petroleum fractions (light to heavy neutral and bright stock) as carrier oil/active ingredients in gasoline additives is known. Their influence on the effectiveness with respect to keep-clean performance in the inlet system of gasoline engines is known to be a function of the concentration.

The demands placed on valve cleanliness and the degree of effectiveness to be achieved have been rising steadily, particularly in recent times, and existing carrier oil technology is no longer adequate to meet these. The octane requirement increase and oil thickening are to be regarded as critical when conventional petroleum fractions are used in higher concentrations.

Variations and combinations of petroleum fractions and fully synthetic carrier oils have hitherto failed to produce satisfactory results.

A known, commercially available additive I on a polyether amine basis (Data Sheet A) has been shown to give satisfactory results in use, but it too failed to show adequate inlet valve keep-clean performance in critical fuels

and in field trials even when applied in the concentration prescribed by the manufacturer.

On the basis of tests with conventional carrier oils as the additional active ingredient (300 sec turbine base oil, Data Sheet B) it was to be expected that an increase in concentration would affect performance, but since the degree to which additive effectiveness can be improved by the addition of carrier oil is limited, and also the amount of carrier oil which can be added is limited by other factors (for example, octane requirement increase, oil thickening and limitation of the metering pump flow rate) and is furthermore dependent on the carrier oil selected, the margin that remains for practically viable solutions is a narrow one.

The task on which the invention is based is -to find an active ingredient which, when used as an extra additive to fuels, increases the effectiveness of the additives hitherto used in respect of keep-clean and cleaning performance, without necessitating a higher additive concentration.

The use of an unconventional, hydrogenated, low-volatility active ingredient in accordance with the invention resulted in a shift of the maximum effectiveness as a function of the concentration towards a distinct improvement in effectiveness, while the base additive was maintained at the same concentration level and the same rate of addition as for conventional carrier oils.

The active ingredients pursuant to the invention lie within a viscosity range at 100°C of 4.0 to 8.0 cST with a viscosity index of 120 to 160. The concentration of the active

2 ingredient pursuant to the invention is between 50 and 1000 ppm/wt, with particular emphasis on the range between 200 and 800 ppm/wt.

Tests with other base additive technologies ( annich bases, Additive II) and succinimide/polyisobutylene (Additive III) in different test engines (MB M102E, Renault F2N, Toyota Camry and BMW 528i) , different test programs and road tests with eight different vehicle models as well as in different fuels showed improvements in effectiveness as a result of adding the active ingredient pursuant to the invention to the relevant base additive.

The table set out below shows the average improvement in effectiveness of the conventional additives I, II and III by the addition of different amounts of the active ingredient pursuant to the invention, achieved in different inlet valve tests and expressed as "improvement in %" compared to the relevant conventional additive technology. By comparison, the improvement obtained by adding conventional carrier oil to additive I is only 6%.

Increased Effectiveness through Addition of the Active

Ingredient

Concen- Additive Concentr. of Active Improvement in tration Ingredient purs. to

Invention in %

0 12 22 38

0 29

0 11

Basically the invention consists in the use of an unconventional, hydrogenated, low-volatility active ingredient as carrier oil with effectiveness-enhancing properties for known gasoline additives of different chemical technology. The improvement in effectiveness clearly exceeds that which could be expected from an increase in the carrier oil concentration and can therefore be attributed to the special quality of the active ingredient pursuant to the invention.

A typical specification of the active ingredient pursuant to the invention is that of a hydrocracked base oil as set out in the following table:

r

Data Sheet A

Conventional Additive I

Gasoline additive for gasoline engine inlet system keep-clean performance, for the purpose of ensuring excellent carburetor keep-clean and cleaning performance with a simultaneous marked reduction in inlet valve deposits. In addition, it provides excellent injection nozzle keep-clean and cleaning performance.

These properties were demonstrated by tests in different gasolines applying different European test methods. These include the Renault R5 carburetor cleanliness test, the Peugeot 205 GTI injection nozzle test, the Opel Kadett, VW Polo and Mercedes Benz M 102E inlet valve test.

The results confirm that Additive I, if used in the recommended concentration, can provide complete control of inlet system cleanliness. Removal of inlet system deposits can improve operability, reduce fuel consumption, restore performance and reduce exhaust emissions.

Recommended concentration:

mg/kg (ml/cu m) : 800 (660) - 1200 (990)

Typical analysis data:

Physical:

Specific gravity at 15°C: 890 g/kg

Vise.40°C: 95 cST 0°C 1100 cST

Flash point, PMCC, °C 47

Chemical data: Nitrogen, wt. ^! 0.42

s

Data Sheet B

Turbine Base Oil

Typical Analysis Data

Test Method Min Typical Max

Colour, ASTM D 1500 2.5

Sp. Grav. 15.6C/15.6C g/ml

Aniline point

Flash point COC

Flash point PM

Pour point

Vise. 40.0°C

Vise. 100.0°C

Viscosity Index

Demuls 5 °C mins (ml-ml-ml)

Ramsbottom Carbon Res. wt' 0.15

Sulphur wt, D 2622 0.70