A lubricating oil composition for an internal combustion engine includes: a lubricant base oil including at least one mineral base oil, at least one synthetic base oil, or any combination thereof, and having a kinematic viscosity at 100° C. of 3.0 to 4.0 mm.sup.2/s and a NOACK evaporation loss at 250° C. of no more than 15 mass %; (A) a calcium-containing metallic detergent in an amount of no less than 1000 mass ppm and less than 2000 mass ppm in terms of calcium; (B) a magnesium-containing metallic detergent in an amount of 100 to 1000 mass ppm in terms of magnesium; (G) a zinc dialkyl dithiophosphate in an amount of no less than 600 mass ppm in terms of phosphorus; and optionally (C) a viscosity index improver in an amount of no more than 5 mass %.

A lubricating oil composition for an internal combustion engine includes: a lubricant base oil including at least one mineral base oil, at least one synthetic base oil, or any combination thereof, and having a kinematic viscosity at 100° C. of 3.0 to 4.0 mm.sup.2/s and a NOACK evaporation loss at 250° C. of no more than 15 mass %; (A) a calcium-containing metallic detergent in an amount of no less than 1000 mass ppm and less than 2000 mass ppm in terms of calcium; (B) a magnesium-containing metallic detergent in an amount of 100 to 1000 mass ppm in terms of magnesium; (G) a zinc dialkyl dithiophosphate in an amount of no less than 600 mass ppm in terms of phosphorus; and optionally (C) a viscosity index improver in an amount of no more than 5 mass %.

A grease composition is intended primarily for use in constant velocity joins (CV joints), especially ball joints and/or tripod joints, which are used in the drivelines of motor vehicles. The grease composition for use in constant velocity joints comprises at least one base oil, and least one thickener, at least one copper sulfide in an amount of approximately 0.01 wt-% up to approximately 1.5 wt-% of the grease composition, molybdenum disulfide and/or at least one phosphorus-free organic molybdenum complex in an amount of approximately 0.1 wt-% up to approximately 5.0 wt-% of the grease composition. Further, a constant velocity joint comprises the grease composition.

A grease composition is intended primarily for use in constant velocity joins (CV joints), especially ball joints and/or tripod joints, which are used in the drivelines of motor vehicles. The grease composition for use in constant velocity joints comprises at least one base oil, and least one thickener, at least one copper sulfide in an amount of approximately 0.01 wt-% up to approximately 1.5 wt-% of the grease composition, molybdenum disulfide and/or at least one phosphorus-free organic molybdenum complex in an amount of approximately 0.1 wt-% up to approximately 5.0 wt-% of the grease composition. Further, a constant velocity joint comprises the grease composition.

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.

A lubricant composition comprising an oil-soluble polyalkylene glycol; an ester compound selected from the group of natural esters and synthetic esters, and combinations thereof; and an additive mixture comprising an antioxidant and an anticorrosive, wherein the anticorrosive is selected from neutral alkali metal and alkaline earth metal salts of sulfonic acids, carboxylic acids, naphthoic acids, naphthenic acids, benzoic acids and phosphoric acids, and derivatives and combinations thereof.

A lubricant composition comprising an oil-soluble polyalkylene glycol; an ester compound selected from the group of natural esters and synthetic esters, and combinations thereof; and an additive mixture comprising an antioxidant and an anticorrosive, wherein the anticorrosive is selected from neutral alkali metal and alkaline earth metal salts of sulfonic acids, carboxylic acids, naphthoic acids, naphthenic acids, benzoic acids and phosphoric acids, and derivatives and combinations thereof.

[Technical Problem] An object is to provide a sliding system which can achieve both the reduced friction and the enhanced wear resistance by means of a novel combination of a sliding film and a lubricant oil.

[Solution to Problem] The sliding system of the present invention comprises: a pair of sliding members having sliding surfaces that can relatively move while facing each other; and a lubricant oil interposed between the sliding surfaces facing each other. At least one of the sliding surfaces comprises a coating surface of a crystalline chromium carbide film. The lubricant oil contains an oil-soluble molybdenum compound that has a chemical structure of a trinuclear of Mo. When the chromium carbide film as a whole is 100 at %, the chromium carbide film contains 40-75 at % of Cr. The chromium carbide film in contact with the lubricant oil containing a Mo-trinuclear appears to react with the Mo-trinuclear adsorbed during the sliding to generate a layered structural body (boundary film) similar to MoS.sub.2 on the surface, thereby developing a considerably low friction property.

The present invention relates to lubricating compositions comprising a compound of Formula I:

##STR00001##

wherein R.sub.1-R.sub.4 and R.sub.5-R.sub.8 are independently selected from the group consisting of hydrocarbyl groups and hydrocarbyl groups containing heteroatoms, such that the total carbon atoms from counterions Q.sub.1 and Q.sub.2 is from 8 to 76, and molybdate anion (Y) is a binuclear sulfur-containing dianion selected from the group consisting of [Mo.sub.2S.sub.8O.sub.2].sup.2−, [Mo.sub.2S.sub.9O].sup.2−, [Mo.sub.2S.sub.10].sup.2−, and mixtures thereof, and are present in the lubricating composition in an amount sufficient to provide about 100-15,000 ppm molybdenum.

The present invention relates to lubricating compositions comprising a compound of Formula I:

##STR00001##

wherein R.sub.1-R.sub.4 and R.sub.5-R.sub.8 are independently selected from the group consisting of hydrocarbyl groups and hydrocarbyl groups containing heteroatoms, such that the total carbon atoms from counterions Q.sub.1 and Q.sub.2 is from 8 to 76, and molybdate anion (Y) is a binuclear sulfur-containing dianion selected from the group consisting of [Mo.sub.2S.sub.8O.sub.2].sup.2−, [Mo.sub.2S.sub.9O].sup.2−, [Mo.sub.2S.sub.10].sup.2−, and mixtures thereof, and are present in the lubricating composition in an amount sufficient to provide about 100-15,000 ppm molybdenum.