I understand that "diesel oil" (CJ rated) has more detergents to better suspend carbon between changes. Oil gets black much faster because of more leakage past the rings at 20:1 compression, and the fuel droplets burn as a sootier "diffusion flame" rather than the ideal "pre-mixed flame" in a gas engine (assuming fine atomization/evaporation and mixing).

Many owners of classic gas cars use diesel oil like Rotella. They consider it better quality and the added zinc helps w/ flat-tappet cams, especially those using racing cams w/ stronger valve springs. Diesel oil used to cost more. Be happy. The fuel is even cheaper than gas currently.

__________________
1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans