Disclosed is a lubricating oil composition for gear oil, comprising a lubricating base oil having a kinematic viscosity at 40 C. of 140 to 350 mm.sup.2/s, a copolymer of an -olefin and an ester monomer having a polymerizable unsaturated bond, a performance additive containing phosphorus and sulfur, and a poly(meth)acrylate pour-point depressant.

A drive device includes a gear having a hole; a shaft that passes through the hole; and a grease composition that is held in a clearance between the shaft and an inner peripheral surface of the hole. The gear rotates on a peripheral surface of the shaft. At least one of the gear and the shaft is made of a resin. The clearance is in a range of 10 to 110 m. The grease composition contains a hydrocarbon base oil and lithium soap serving as a thickener. A weight ratio of the hydrocarbon base oil to the lithium soap is in a range of 94.5:5.5 to 96.0:4.0. A consistency of the grease composition is in a range of 360 to 400.

A method for preventing or reducing engine knock or pre-ignition in a high compression spark ignition engine lubricated with a lubricating oil by using as the lubricating oil a formulated oil. The formulated oil has a composition that contains at least one branched hydrocarbon having at least about 25% of the carbons in the form of methyl groups, or at least one polyol ester of at least one branched mono-carboxylic acid. A lubricating engine oil having a composition that contains at least one branched hydrocarbon having at least about 25% of the carbons in the form of methyl groups, or at least one polyol ester of at least one branched mono-carboxylic acid. The lubricating engine oils are useful as passenger vehicle engine oil (PVEO) products.

There is provided a grease composition for improving the chemical stability of the grease composition and increasing the fatigue life of a member in which the grease composition is used. The problems can be solved by a grease composition including a poly--olefin; a urea-based thickener; molybdenum dithiophosphate; and barium sulfonate, wherein a difference between an SP value of the urea-based thickener and an SP value of the poly--olefin is 3.5 or less.

This ball screw grease composition for a rack-assisted electric power steering contains a thickener, a base oil, and at least one compound selected from the group consisting of a Ca sulfonates, fatty acids, and triglycerides, wherein the kinematic viscosity of the base oil at 40? C. is 4-100 mm2/s, and the worked penetration of the composition is 265-385.

A method for preventing or reducing engine knock or pre-ignition in a high compression spark ignition engine lubricated with a lubricating oil by introducing to a combustion chamber of the engine from 0.1 to 5% by volume of the gasoline used a lubricating oil as a formulated oil, said formulated oil having a composition comprising (i) a major amount of a lubricating oil base stock comprising at least 80% by weight of one branched ester having at least 15% of the total carbons in the form of methyl groups, and (ii) a minor amount of at least one ashless amine phosphate antiwear additive. Also provided is a lubricating engine oil for high compression spark ignition engines including (i) a major amount of a lubricating oil base stock comprising at least 80% by weight a trimethylol propane ester of 50:50 mixture of isobutyric acid and 3,5,5-trimethylhexanoic acid and (ii) a minor amount of at least one amine phosphate ashless antiwear additive.

The present invention relates to the use of highly viscous (per)fluoropolyether polymers as damping fluids and to a method for counteract vibrations and/or shocks in a device using highly viscous (per)fluoropolyether polymers.

A grease of the invention contains a base oil and a thickener, where, when the volumetric-based arithmetic mean particle size of particles contained in the grease measured using laser diffraction/scattering method is A (unit: m), a formula A3 (1) is satisfied.

The invention provides a lubricating grease composition comprising an oil of lubricating viscosity, a metallic soap thickener and a boron-containing compound, wherein the boron containing compound comprises a borate ester comprising at least one alkyl group having a branch at the position or higher. The invention further relates to a method of lubricating a mechanical device with the lubricant composition.

The present patent application relates to the use, as detergent additive in a lubricating composition intended for a marine engine, of at least one spiro compound of formula (I)

##STR00001## in which M is an atom chosen from boron and aluminum; n1 and n2 have, independently of one another, the value 0, 1 or 2; and R represent, independently of one another, a hydrocarbon group comprising from 1 to 50 carbon atoms, in particular from 5 to 20 carbon atoms.

It also relates to the use of said spiro compound as additive in a lubricating composition intended for a marine engine, for improving the stability to oxidation of said lubricating composition.

Finally, it relates to a lubricating composition intended for the lubrication of a marine engine, comprising one or more base oils and at least one spiro compound of formula (I), and also to a process of lubrication of a marine engine employing such a composition.