A crankcase lubricating oil composition for the crankcase of a spark-ignited or compression-ignited internal combustion engine, comprising a magnesium-containing detergent, in an amount sufficient to provide from 200-4000 ppm magnesium to the lubricating oil composition, in combination with an oil-soluble or oil-dispersible molybdenum compound in an amount sufficient to provide from 600-1500 ppm molybdenum atoms to the lubricating oil composition, and with an oil-soluble or oil-dispersible boron-containing compound in an amount sufficient to provide from 200-600 ppm boron atoms to the lubricating oil composition to improve the friction and fuel economy performance.

A composition is obtained by mixing at least one oligomer A1, which is obtained by copolymerizing at least two monomers functionalized by diol functions with at least one second monomer, with at least one compound A2 having at least two boron ester functions. The compositions exhibit very varied rheological properties depending on the proportion of the compounds A1 and A2 used. A composition is also obtained by mixing at least one lubricating oil with such a composition of associative and exchangeable polymers, and the use of this composition to lubricate a mechanical part.

A composition is obtained by mixing at least one oligomer A1, which is obtained by copolymerizing at least two monomers functionalized by diol functions with at least one second monomer, with at least one compound A2 having at least two boron ester functions. The compositions exhibit very varied rheological properties depending on the proportion of the compounds A1 and A2 used. A composition is also obtained by mixing at least one lubricating oil with such a composition of associative and exchangeable polymers, and the use of this composition to lubricate a mechanical part.

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 an 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 an ashless dispersant. The ashless dispersant may be selected from succinimide compounds prepared from aliphatic or aromatic amines.

The present disclosure describes lubricant compositions effective to minimize average engine sludge through selection of lubricant additives that control the total nitrogen as well as the origin of the nitrogen in the lubricant composition. In aspects, the lubricant compositions herein include at least a base oil of lubricating viscosity, a dispersant system, and at least one antioxidant.

The present disclosure describes lubricant compositions effective to minimize average engine sludge through selection of lubricant additives that control the total nitrogen as well as the origin of the nitrogen in the lubricant composition. In aspects, the lubricant compositions herein include at least a base oil of lubricating viscosity, a dispersant system, and at least one antioxidant.

Provided is a lubricating oil composition to be used in an internal combustion engine having a sliding mechanism including a piston ring and a liner, the lubricating oil composition including: a base oil; (A) a poly(meth)acrylate; and (B) an organic molybdenum compound, in which: (A) the poly(meth)acrylate contains a polymer (A1) including a repeating unit derived from a (meth)acrylate represented by the following formula (1) and having a mass-average molecular weight of from 1,000 to 500,000; and a content of (B) the organic molybdenum compound in a total amount of the composition is from 0.01 mass % to 0.2 mass % in terms of a molybdenum atom: wherein R.sup.1 represents a hydrogen atom or a methyl group, and X represents a hydrogen atom, a hydrocarbon group having 1 to 60 carbon atoms, or a functional group-containing hydrocarbon group having 1 to 60 carbon atoms.

Provided is a lubricating oil composition to be used in an internal combustion engine having a sliding mechanism including a piston ring and a liner, the lubricating oil composition including: a base oil; (A) a poly(meth)acrylate; and (B) an organic molybdenum compound, in which: (A) the poly(meth)acrylate contains a polymer (A1) including a repeating unit derived from a (meth)acrylate represented by the following formula (1) and having a mass-average molecular weight of from 1,000 to 500,000; and a content of (B) the organic molybdenum compound in a total amount of the composition is from 0.01 mass % to 0.2 mass % in terms of a molybdenum atom: wherein R.sup.1 represents a hydrogen atom or a methyl group, and X represents a hydrogen atom, a hydrocarbon group having 1 to 60 carbon atoms, or a functional group-containing hydrocarbon group having 1 to 60 carbon atoms.

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 an ashless dispersant. The ashless dispersant may be selected from succinimide compounds prepared from aliphatic or aromatic amines.