Patent ID: 7956021

Claim:
A lubricating oil composition comprising a base oil of lubricating viscosity having a kinematic viscosity of 22 to 300 mm 2 /s at 40° C. and dissolved or dispersed therein the following additives in the following amounts based on a total amount of the lubricating oil composition: (1) an overbased sulfurized alkylphenol calcium salt detergent in an amount of 0.5 to 1.0 wt. % in terms of calcium content, (2) an overbased calcium alkylbenzenesulfonate detergent in an amount of 1.5 to 2.1 wt. % in terms of calcium content, (3) a nitrogen-containing ashless dispersant in an amount of 0.005 to 0.1 wt. % in terms of nitrogen content, and (4) a zinc dihydrocarbyldithiophosphate in an amount of 0.007 to 0.1 wt. % in terms of phosphorus content, wherein the weight ratio of the overbased sulfurized alkylphenol calcium salt detergent to the overbased calcium alkylbenzenesulfonate detergent is in the range of 22:78 to 37:63 in terms of calcium content and wherein the lubricating oil composition has a total base number of 60 to 100 mg·KOH/g.