Disclosed is a dispersant composition, suitable for use in lubricating oils. The dispersant composition is a reaction product of (i) a polyalkenyl succinimide post-treated with a post-treating agent selected from the group consisting of an organic carbonate, an epoxide, a lactone, a hydroxyaliphatic carboxylic acid, and combinations thereof; and (ii) an acylating agent.

Disclosed is a dispersant composition, suitable for use in lubricating oils. The dispersant composition is a reaction product of (i) a polyalkenyl succinimide post-treated with a post-treating agent selected from the group consisting of an organic carbonate, an epoxide, a lactone, a hydroxyaliphatic carboxylic acid, and combinations thereof; and (ii) an acylating agent.

The invention is directed to a method for reducing low speed pre-ignition events in a spark-ignited direct injection internal combustion engine by supplying to the sump a lubricant composition which contains an oil of lubricating viscosity and a boron-containing ashless dispersant. The ashless dispersant may be selected from succinimide compounds prepared from aliphatic or aromatic amines.

The invention is directed to a method for reducing low speed pre-ignition events in a spark-ignited direct injection internal combustion engine by supplying to the sump a lubricant composition which contains an oil of lubricating viscosity and a boron-containing ashless dispersant. The ashless dispersant may be selected from succinimide compounds prepared from aliphatic or aromatic amines.

A lubricating oil composition comprises a major amount of an oil of lubricating viscosity and a minor amount of an unsymmetrical bis-succinimide, or a mixture of unsymmetrical bis-succinimides, of the structure (I): ##STR00001##
wherein one of R.sub.1 and R.sub.2 is a polyisobutylene group having a weight average molecular weight of 400 to 5,000, as determined by GPC with reference to linear polystyrene standards, and the other of R.sub.1 and R.sub.2 is a hydrocarbon group made by the metallocene-catalysed polymerisation of an -olefin feedstock; and x is from 1 to 10 and is the same for all molecules of structure (I), or an average of all molecules of structure (I) in a mixture of molecules of structure (I).

The invention relates to the use of quaternized nitrogen compounds as a fuel and lubricant additive or kerosene additive, such as in particular as a detergent additive, for decreasing or preventing deposits in the injection systems of direct-injection diesel engines, in particular in common rail injection systems, for decreasing the fuel consumption of direct-injection diesel engines, in particular of diesel engines having common rail injection systems, and for minimizing the power loss in direct-injection diesel engines, in particular in diesel engines having common rail injection systems; the invention further relates to the use as an additive for petrol, in particular for operation of DISI engines.

The invention relates to the use of quaternized nitrogen compounds as a fuel and lubricant additive or kerosene additive, such as in particular as a detergent additive, for decreasing or preventing deposits in the injection systems of direct-injection diesel engines, in particular in common rail injection systems, for decreasing the fuel consumption of direct-injection diesel engines, in particular of diesel engines having common rail injection systems, and for minimizing the power loss in direct-injection diesel engines, in particular in diesel engines having common rail injection systems; the invention further relates to the use as an additive for petrol, in particular for operation of DISI engines.

A method for improving wear control of a steel surface lubricated with a lubricating oil through the generation of thick tribofilms. The method includes: (i) using as the lubricating oil a formulated oil, the formulated oil having a composition comprising at least one lubricating oil base stock as a major component; and at least one lubricating oil additive, as a minor component; and (ii) forming a tribofilm on the steel surface. In time-step tribofilm formation measurements of the lubricating oil by a mini-traction machine (MTM) at constant slide-to-roll ratio (SRR), the saturation traction coefficient (f.sub.s), which correlates to tribofilm thickness on the steel surface, is greater than about 0.11. In the method of this disclosure, elongation of timing chain due to wear of chain link pins is less than about 0.07%, as determined by Ford Chain Wear (FCW) test conducted in accordance with ILSAC GF-6 specification. The lubricating oils are useful in internal combustion engines.

A method for improving wear control of a steel surface lubricated with a lubricating oil through the generation of thick tribofilms. The method includes: (i) using as the lubricating oil a formulated oil, the formulated oil having a composition comprising at least one lubricating oil base stock as a major component; and at least one lubricating oil additive, as a minor component; and (ii) forming a tribofilm on the steel surface. In time-step tribofilm formation measurements of the lubricating oil by a mini-traction machine (MTM) at constant slide-to-roll ratio (SRR), the saturation traction coefficient (f.sub.s), which correlates to tribofilm thickness on the steel surface, is greater than about 0.11. In the method of this disclosure, elongation of timing chain due to wear of chain link pins is less than about 0.07%, as determined by Ford Chain Wear (FCW) test conducted in accordance with ILSAC GF-6 specification. The lubricating oils are useful in internal combustion engines.

Engine oil \s and methods for use in soot-producing engines. The engine oil contains a major amount of a base oil and a dispersant reaction product of A) a hydrocarbyl-dicarboxylic acid or anhydride, and B) at least one polyamine, that is post-treated with C) an aromatic carboxylic acid, an aromatic polycarboxylic acid, or an aromatic anhydride, wherein all carboxylic acid or anhydride groups of C) are attached directly to an aromatic ring. A molar ratio of carboxyl groups from components A) and C) to nitrogen atoms from component B) of from 0.9 to 1.3 is used to make the dispersant which also has a molar ratio of component C) to component B) of at least 0.4 and when component B) has an average of 4-6 nitrogen atoms per molecule, a molar ratio of A) to B) is from 1.0 to 1.6.