Rotella 15w40

diesel oil use to be good for flat tappet cams back when a cummins had 300+ lbs on the injector lobes of the cam but that faded out in the early 90s and ecm controlled injectors and roller cams are the standerd now in every engine mfg and the heavy zinc ant used no more, with accordance of epa mandates on oil! the few folks that still trying to run the older diesels looking at oils just as hard as us hotroders, alot use the lucas hotrod high zinc oil some using valvoline blue or delo 400 still, mobil 1 has been detroits go to since the 60 series came out in late 80s with extended drain intevers upwards of 50,000 to 70,000 miles! thats some damn fine oil but is that what a race motor needs or a street strip motor??? no it ant! brad penn, joe gibbs, scheffer, royal purple what an all out race motor needs,..rest be some wheres in the middle....