Lubricating oil composition for internal combustion engines

摘要

The invention provides a lubricant oil composition useful for reduction in friction loss and improvement in fuel economy in internal combustion engines, particularly, a lubricant oil composition for internal combustion engines exhibiting an excellent friction reducing effect even in a diesel engine equipped with EGR accompanied with an increase in soot content in oil. The invention is a lubricant composition for internal combustion engines comprising a lubricant base oil consisting of a mineral oil and/or synthetic oil or the like incorporated with 1 wt % or more, based on the total weight of the lubricant oil composition, a nonionic surfactant with alkylene oxide added thereto consisting of at least one compound having an HLB value of 15 or more and a molecular weight of 900 or more, and a friction reducing method for internal combustion engines using this lubricant oil composition.