| 摘要 |
PROBLEM TO BE SOLVED: To obtain a lubricating oil composition for an internal combustion engine which, when it is fresh, has excellent friction reducing effect, is capable of showing this effect for a long term and shows reduced fuel consumption by mixing a lubricating base oil with three specified components. SOLUTION: The lubricating base oils used are ones based on mineral oils and ones based on synthetic oils. The mineral-oil-based one is exemplified by a paraffinic oil prepared by refining the lubricating oil fraction obtained by distilling crude oil, and the synthetic-oil-based one is exemplified by polyα-olefin. These are suitably mixed with each other to form a mixture having a kinematic viscosity of 1-100mm<2> /s at 40 deg.C. A composition containing 0.01-5.0wt.%, based on the entire weight of the composition, zinc dihydrocarbyldithiophosphate (A) represented by formula I (wherein R<1> to R<4> are each a 1-18C hydrocarbon group, 0.01-5.0wt.% molybdenum dialkyldithiocarbamate (B) represented by formula II (wherein R<5> to R<8> are each a 1-18C alkyl; and X<1> to X<4> are each S or O) and 0.005-1.0wt.% copper carboxylate (C) represented by formula III (wherein R<9> and R<10> are each a 1-24C hydrocarbon group) is prepared. Components B and C are brought into contact with each other at 40-100 deg.C in the absence of Component A. This composition is added to a lubricating base oil. |
