Lubricating oil composition

摘要

To provide a lubricating oil composition including a base oil which is composed of a mineral oil and/or a synthetic oil and which has a viscosity index of 95 or higher, and (A) an alkenylsuccinimide in an amount of 0.1 to 2.0 mass %, (B) an acidic phosphite diester having a C6 to C10 hydrocarbon group in an amount of 0.1 to 2.0 mass %, and (C) at least one species selected from among a perbasic alkaline earth metal sulfonate, a perbasic alkaline earth metal phenate, and a perbasic alkaline earth metal salycilate, in an amount of 0.001 to 0.3 mass %, with respect to the total amount of the composition. When employed in an automobile shock absorber, the composition enhances the frictional force at an interface between an oil seal and a piston rod of an automobile shock absorber, reduces the friction coefficient at an interface between a piston rod and a guide bush, suppresses foaming to thereby enhance driving stability during travel of the automobile, and improves riding comfort even when the automobile travels while receiving a lateral load exerted by small steps present on the road surface.

主权项

1. A lubricating oil composition comprising:
a base oil comprising a mineral oil and/or a synthetic oil and which has a viscosity index of 95 or higher and a flash point of 150° C. or higher; (A) an alkenylsuccinimide in an amount of 0.1 to 2.0 mass %; (B) an acidic phosphite diester having the formula: wherein each of R7 and R8 represents a C8 hydrocarbon group, in an amount of 0.3 to 2.0 mass %; and (C) at least one species selected from the group consisting of a perbasic alkaline earth metal sulfonate and a perbasic alkaline earth metal phenate, in an amount of 0.001 to 0.3 mass %, with respect to the total amount of the composition, wherein in a test of the lubricating oil composition in a Bouden-type reciprocating kinetic friction tester, the friction coefficient (μI) of a seal member is at least 0.31, and wherein in a test of the lubricating oil composition in a crank-type reciprocating kinetic friction tester, the friction coefficient (μII) of a guide bush is no greater than 0.40.