the oil company does not tell you the whole truth. They haven’t reduced their ZDDP additive but they have had to add a D.P.F. (Diesel particulate Filter) additive package and other additive package to the current diesel oil CJ-4 API rating. These additives fight against the formation of the ZDDP anti-wear film. In low RPM diesel engines this is not a problem. However, in gasoline engines that run at higher (over 3,000) rpms it is a problem.
