Abstract: A lubricating oil composition for fluid dynamic bearings which comprises 50 to 100% by mass of an ether compound comprising at least one ether bond and having 11 to 34 carbon atoms as the base oil and has a kinematic viscosity of at least 2.2 mm2/s at 100° C. is provided. The composition has excellent viscosity characteristics such as excellent fluidity at low temperatures and a small decrease in the viscosity in a high temperature range, exhibits lower evaporability, excellent energy saving property and excellent heat stability and is advantageously used for compact fluid dynamic bearings used under rotation at a high speed.

Abstract: A lubricating oil composition contains: an ester as a base oil formed from a dibasic acid having a carbon number of 9 to 12 and a primary alcohol having a side chain and a carbon number of 8 to 13; and an alkyl(metha)acrylate polymer having an SP (solubility parameter) value of 9.2 or higher and a mass average molecular weight of 1×105 to 1×106, the alkyl(metha)acrylate polymer being contained in an amount of 0.5 to 10 mass % of a total amount of the composition. A viscosity of the composition at 100° C. is 9.3 to 11.5 mm2/s.

Abstract: A metal working oil composition having a kinematic viscosity of 20 cSt or less at a temperature of 40.degree. C. is herein disclosed which comprises (A) 10% by weight or more of an n-.alpha.-olefin (e.g. 1-hexadecene) and (B) an overbased sulfonate having a total base number of 350 mg.multidot.KOH/g or more in such an amount that the total base number of the composition is 12.5 mg.multidot.KOH/g or more. The metal working oil composition is particularly suitable as a press lubricant for aluminum alloys, has an excellent mass workability, and is more excellent in coating workability, lubricity, degreasing properties, weldability, etc. than a conventional solid coating type lubricant.

Abstract: A fluid composition for use in a shock absorber is described, comprising (a) a lubricating base oil, (b) 10 to 1,000 ppm, as calculated as boron, of a boron-containing compound, and (c) 100 to 3,000 ppm, as calculated as phosphorus, of phosphoric acid ester and/or phosphorous acid ester. The invention also provides a shock absorber containing said fluid composition as the shock absorber fluid. This shock absorber has the advantage of high abrasion resistance and a low coefficient of friction of movement of the movable parts relative to the stationary parts therein.