Lubricating oil composition for automatic transmissions

摘要

There is disclosed a lubricating oil composition for automatic transmissions which comprises a base oil comprising at least one oil selected from the group consisting of a mineral oil and a synthetic oil each having a specific kinematic viscosity and a % CA; (A) a non-boron based succinic acid imide (e.g. polybutenylsuccinic acid imide) and a boron based succinic acid imide each in an amount of 0.1 to 5% by weight based on the whole composition; (B) a condensation product of a branched chain fatty acid having 8 to 30 carbon atoms (e.g. isostearic acid) and an amine (e.g. tetraethylene-pentamine) in an amount of 0.05 to 2% by weight based on the same; and (C) a dialkyl hydrogenphosphite (e.g. dioleyl hydrogenphosphite) in an amount of 0.1 to 1% by weight based on the same, and optionally at least one member selected from viscosity index improvers, antioxidants, metal deactivators, defoaming agents, detergents, extreme pressure agents and rust preventives. The lubricating oil composition mentioned above is enhanced in the capacity of transmission torque, excellent in the performance of preventing shudder, and prolonged in the service lifetime of shudder prevention and capacity of transmission torque.