Originally Posted By: CompSyn
Could one not look at the 4-ball test and make some sort of "assumption" regarding an engine that uses a flat-tappet camshaft and the extreme pressure loads therein?
Yes actually you could. Not an "assumption" - rather a correlation. For example, a properly formulated oil with 1400 ppm Zn, 1200 ppm P could do better than a borderline formulated oil with 700 ppm Zn/P that has wiped cams. It's a rough correlation to be sure, that's why the test is used by oil companies and additive manufacturers at the early lower levels of formulation.