To solve a problem of demanding an additive compensating for the ability of engine oil, which is deteriorated by the reduction in sulfur functioning as an antioxidizing agent in the context of looking for many openings, such as improvement in fuel saving performance and purification of and reduction in emission gases, by the automotive industry in order to address environmental problems such as global warming, including the reduction in sulfur content in lubricant base oil, where a base oil with much sulfur content sometimes causes emission of hazardous materials such as sulfur oxides into the environment.
The lubricating oil composition according to the present invention comprises a novel phosphomolybdic compound and the base oil with a sulfur content of 200 ppm. Because a small amount of the novel phosphomolybdic compound shows ability equal to or better than that of an existing antioxidizing agent, the compound can improve a lubricant oil in the antioxidant ability without increasing the metal content in the lubricant oil.
IINO MASASHI
YAMAMOTO KENJI
SAIBI YOSHIHIDE
