I used to use Rotella T for my 87 300 SDL and 80 240D, but now I use Delo 1300 super for my 80 240D and 83 300D. Someone posted data on rotella T, Delo and one other maybe six months ago.

IIRC, Delo 1300 was superior. And it's available at MegaloMart (walmart) for $5.88/gal.

Joe