Abstract: Lubricating oil composition for internal combustion engines includes a base oil containing (A) 30-98% by weight of a mineral oil having a kinematic viscosity of 2-30 mm.sup.2 /sec at 100.degree. C. and a viscosity index of not less than 100 and (B) 2-70% by weight of poly-.alpha.-olefin, and zinc dithiophosphate in an amount corresponding, as reduced to the amount of P (phosphorus), to 0.02-0.15 parts by weight with respect to 100 parts by weight of the base oil. The composition of the present invention is advantageously used as lubricating oil composition for internal combustion engines, exerting excellent effects in terms of the consumption of the oil composition, fuel consumption rate, and sealing characteristics of rubber.

Abstract: A lubricating oil composition is herein disclosed which comprises (a) a base oil comprising a mineral oil, a synthetic oil or both the oils, (b) a copolymer having repeating units of the formulae (I) and (II) ##STR1## (c) an amine-based antioxidant, and if necessary, (d) a thiadiazole compound. The repeating unit of the formula (I) is derived from a monomer such as dimethylamino methacrylate. The repeating unit of the formula (II) is derived from a monomer such as a methacrylate of a long-chain alcohol. R.sup.1 and A may be the same or different every repeating unit. This lubricating oil composition is minimized in change with the lapse of time in frictional characteristics (shift shock in an automatic transmission or the like) and is excellent in oxidation stability.

Abstract: The present invention provides a lubricating oil composition characterized in that the base oil contains (A) from 0.05 to 5% by weight of an ester of alkenyl substituted succinic acid and/or an ester of alkyl substituted succinic acid and (B) from 0.005 to 5% by weight of a fatty acid ester of a polyhydric alcohol. The lubricating oil composition of the present invention has a friction characteristic in which the (coefficient of static friction)/(coefficient of dynamic friction) ratio is small and gives only a small shock by shift change. In addition, the changes in the friction characteristics depending on the oil temperature is small and also the changes in the lapse of time are small. Accordingly, it is fully compatible with the trend toward a compact size of transmissions and the like.

Abstract: A lubricating oil composition comprising: (A) a base oil having a naphthene content of at least 30%, an aromatic content of not more than 2%, and a kinematic viscosity at 100.degree. C. of 1.5 to 30 cSt; and (B) 0.01 to 5% by weight based on the total weight of the composition of a friction modifier. This composition is very useful as a lubricating oil for use in an automatic transmission or a continuously variable transmission, or as a lubricating oil for use in parts including a wet clutch or a wet brake of an agricultural tractor, etc.

Abstract: A lubricating oil composition comprising: (A) a base oil having a naphthene content of at least 30%, an aromatic content of not more than 2%, and a kinematic viscosity at 100.degree. C. of 1.5 to 30 cSt; and (B) 0.01 to 5% by weight based on the total weight of the compositon of a friction modifier. This composition is very useful as a lubricating oil for use in an automatic transmission or a continuously variable transmission, or as a lubricating oil for use in parts including a wet clutch or a wet brake of an agricultural tractor, etc.