LUBRICATING OILS, LUBRICATING OIL COMPOSITIONS, AND FUEL OILCOMPOSITIONS

摘要

The lubricating oil of the invention comprises an .alpha.- olefin/aromatic vinyl compound random copolymer comprising constituent units derived from ethylene, constituent units derived from an aromatic vinyl compound and optionally constituent units derived from an .alpha.-olefin of 3 to 20 carbon atoms in specific proportions and having an intrinsic viscosity, as measured in decalin at 135 .degree.C, of 0.01 to 0.50 dl/g. The lubricating oil is excellent in compatibility with lubricating oil additives as well as in viscosity properties, heat stability, oxidation stability and abrasion resistance. The lubricating oil composition of the invention comprises an .alpha.-olefin/aromatic vinyl compound random copolymer and a base oil. The random copolymer comprises the same constituent units as in the above-mentioned random copolymer in specific proportions and has an intrinsic viscosity, as measured in decalin at 135 .degree.C, of 0.1 to 5.0 dl/g, and the base oil comprises a mineral oil and/or a hydrocarbon synthetic oil. The lubricating oil composition has excellent lubricating oil properties. The fuel oil composition of the invention comprises an .alpha.-olefin/aromatic vinyl type fuel oil fluidity improver and a middle fraction fuel oil having a boiling point of 150 to 400 .degree.C. The fuel oil fluidity improver comprises an .alpha.- olefin/aromatic vinyl compound random copolymer comprising the same constituent units as in the above-mentioned random copolymer in specific proportions and having an intrinsic 66 viscosity, as measured in decalin at 135 .degree.C, of 0.01 to 1.0 dl/g. The fuel oil composition is prevented from viscosity increase of the middle fraction fuel oil and is lowered in the cold filter plugging point and the pour point. Besides, the fuel oil composition contributes to inhibition of abrasion of fuel injection nozzles.