Disclosed is an additive for lubricating oil, which comprises a phosphite ester compound (A) having a specific structure and a phosphite ester compound (B) having a specific structure, wherein a mass ratio of the phosphite ester compound (A) to the phosphite ester compound (B) (phosphite ester compound (A):phosphite ester compound (B)) is 99:1 to 80:20. According to the present invention, it is possible to provide an additive for lubricating oil, capable of imparting wear resistance and demulsibility with respect to a base oil for lubricating oil, and to impart durability even in the presence of water.

Provided is a grease composition which contains (A) a mixed base oil containing (A1) a low-viscosity base oil having a kinematic viscosity at 40° C. of 10 to 50 mm.sup.2/s and (A2) a high-viscosity base oil having a kinematic viscosity at 40° C. of 200 to 700 mm.sup.2/s, (B) a lithium-based thickener and (C) a polymer having a kinematic viscosity at 100° C. of 1,000 to 100,000 mm.sup.2/s, and has an apparent viscosity at −10° C., as measured according to JIS K2220:2013 and at a shear rate of 10 s.sup.−1, of 50 to 250 mPa.Math.s. The grease composition is excellent in pumpability and is also excellent in wear resistance under poor lubrication conditions.

There is disclosed an antifoam component for a mechanical device which includes a fluorinated poly(acrylate) copolymer. The antifoam component has improved foam performance and thermal stability in finished fluids, such as driveline fluids.

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 %.

The invention relates to a grease composition having a base oil and a thickener that includes hydrophilic metal oxide particles and one or more esters which contain one or more unsaturated C—C bonds and/or at least one OH group. The hydrophilic metal oxide particles have a BET specific surface area of at least 10 m.sup.2/g and at least 80% of the hydrophilic metal oxide particles have a particle size in the range of from 5 nm to 900 μm. The amount of the thickener is in the range of from 0.1-40% by weight, based on the total weight of the grease composition. The invention further relates to methods for manufacturing the grease compositions, and the use of the grease compositions for lubricating bearings, gears and couplings.

A high-molecular-weight compound having a plurality of polymer chains linked through a divalent or higher-valent linking group, in which the divalent or higher-valent linking group has a thiol group and at least one of a thioether structure and a thiourethane structure, and a ratio of an absolute weight-average molecular weight to a relative weight-average molecular weight (absolute Mw/relative Mw) of the high-molecular-weight compound is 1.25 or more; and a method for producing the same are provided.

A high-molecular-weight compound having a plurality of polymer chains linked through a divalent or higher-valent linking group, in which the divalent or higher-valent linking group has a thiol group and at least one of a thioether structure and a thiourethane structure, and a ratio of an absolute weight-average molecular weight to a relative weight-average molecular weight (absolute Mw/relative Mw) of the high-molecular-weight compound is 1.25 or more; and a method for producing the same are provided.

A lubricant composition comprising: (i) silver or gold nanoparticles, each of which is encapsulated by a layer of alkylthiol or alkylamine molecules; (ii) palladium or platinum nanoparticles, each of which is encapsulated by a layer of alkylthiol or alkylamine molecules; and (iii) a fluid in which components (i) and (ii) are present. Further described are methods for applying the lubricant composition onto a mechanical device for which lubrication is beneficial, with resulting improvement in friction and wear reduction and/or corrosion inhibition.

The present patent application relates to a method for reducing wear and tear on mechanical parts that are in contact with each other in an internal combustion engine by using a lubricating composition comprising: at least one base oil; at least one oxothiomolybdate salt; and at least one anti-wear compound;
wherein at least one of the said parts includes a surface that comprises an amorphous carbon type coating.

A grease composition including: a base oil; a thickener; a zinc sulfonate; a polysulfide; an overbased calcium sulfonate; and triphenyl phosphite, in which a proportion of the zinc sulfonate with respect to a total mass of the base oil and the thickener is 0.030 mass% to 0.045 mass% in terms of a zinc content, a proportion of the polysulfide with respect to the total mass of the base oil and the thickener is 0.16 mass% to 0.24 mass% in terms of a sulfur content, a proportion of the overbased calcium sulfonate with respect to the total mass of the base oil and the thickener is 0.010 mass% to 0.015 mass% in terms of a calcium content, and a proportion of the triphenyl phosphite with respect to the total mass of the base oil and the thickener is 0.24 mass% to 0.36 mass%.