Abstract: A lubricating oil composition for internal combustion engines which comprises a base oil comprising mineral oils and/or synthetic oils and polyisobutylene having a weight-average molecular weight of 500,000 or higher. Consumption of the engine oil can be decreased by using the above composition. In particular, consumption of the engine oil can be decreased even when the above composition is used as the engine oil of the energy saving type using a base oil having a low viscosity.

Abstract: A lubricating oil composition for internal combustion engines which comprises a base oil comprising mineral oils and/or synthetic oils and polyisobutylene having a weight-average molecular weight of 500,000 or higher. Consumption of the engine oil can be decreased by using the above composition. In particular, consumption of the engine oil can be decreased even when the above composition is used as the engine oil of the energy saving type using a base oil having a low viscosity.

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 for two-cycle engines comprising(A) 40 to 90% by weight of one or more polymers selected from the group consisting of copolymers of ethylene and an .alpha. -olefin and polymers of an .alpha. -olefin having 6 to 18 carbon atoms;(B) 0 to 50% by weight of a polybutene having a kinematic viscosity of 2 to 600 cSt as measured at 100.degree. C.;(C) 5 to 50% by weight of a hydrocarbonaceous solvent having a boiling point not higher than 300.degree. C.; and(D) 2 to 20% by weight of a lubricating oil additive for two-cycle engines.The lubricating oil composition for two-cycle engines excels in both cleanliness and anti-seizure property.