| 摘要 |
PROBLEM TO BE SOLVED: To obtain a lubricating oil composition which exhibits good rust prevention and wet filterability by compounding a base oil with a neutral rust preventive, a rust preventive system containing a specific compound, and an ashless dispersant. SOLUTION: The rust preventive system contains a compound represented by formula I or II [wherein Z is R1R2CH- (wherein R1 and R2 are each 34C or lower hydrocarbyl provided the total number of carbon atoms of them is 11 to 35)]. A hydrocarbyl ester represented by the formula: R(COOR')n (wherein R and R' are each about 40C or lower hydrocarbyl or hydroxyhydrocarbyl; and n is 1 to 4) is suitable as the neutral rust preventive. Each ingredient is added directly or in the form of a concentrate to the base oil. Irrespective of the form of ingredients, the wt. ratio of the neutral rust preventive to the rust preventive system is usually (3:1)-(8:1). The wt. ratio of (the neutral rust preventive + the rust preventive system) to the ashless dispersant is usually (7.5:1). Moreover, a 20C or higher aliphatic carboxylic acid or carboxylic anhydride is compounded. |
