Lubricating oil additive comprising succinimide compound, and its use for diesel engines

摘要

Disclosed are novel succinimide compounds effective in diesel engine lubricating oil for protecting engine parts from being corroded or worn by SOx. An acid compound of formula (I) or (II) is reacted with a polyamine to produce the succinimide compounds, which give an absorption peak ( alpha -peak) at 1640 +/- cm<-1> and an absorption peak ( beta -peak) at 1700 +/- 10 cm<-1> in the IR spectral pattern with the ratio, alpha -peak intensity/ beta -peak intensity, of being 0.12 or more. Ä1Ü R is an alkenyl or alkyl group derived from a C2 to C15 olefinic polymer and having a number-average molecular weight of from 200 to 4000. The succinimide compound is added to base oil along with a metallic detergent-dispersant additives selected from over-based sulfonates, phenates and salicylates of alkaline earth metals to give a lubricating oil composition for diesel engines.