71 198 slant six oil

inexpensive Rotella 15-40 has 1200ppm but is a diesel oil (and has a high viscosity index)) and of course Mobil-1 high mileage. Google oil zinc content. zinc additives are about 1000ppm per 3.2oz so they say 16oz increases ppm to 5000 but Im not sure if that is per 5 quarts or per qt. If your cam is broken in, its already work hardened and will survive todays oil. Breaking in a cam today would be safe using these higher zinc oils. Rollers need not apply.