LUBRICANT COMPOSITIONS FOR AN AUTOMATIC TRANSMISSION

摘要

A lubricant composition for an automatic transmission is provided to improve durability of the friction characteristic, fuel efficiency, and the fatigue life time of a gear. A lubricant composition for an automatic transmission consists of lubricant base oil(A) having kinematic viscosity of 3.7~4.1mm^2/s at 100 deg.C and consisting of lubricant base oil having kinematic viscosity of 2.5~4.5mm^2/s at 100 deg.C and lubricant base oil having kinematic viscosity of 10~40mm^2/s at 100 deg.C; a poly(metha)acrylate viscosity index improver of 1~20wt.% having weight average molecular weight of 15000~30000, to the total weight percent of the composition; an imide friction modifier of 2~4wt.% having a hydrocarbon group with 8~30 carbons; a phosphorous extreme pressure additive of 0.01~0.04wt.%; and an ashless dispersing agent of 0.01~0.04wt.% having at least one of alkyl and alkenyl groups with number average molecular weight over 2000. The lubricant composition has kinematic viscosity of 5.6~5.8mm^2/s at 100 deg.C.