Since the introduction of the new CJ-4 / SM motor oils, there has been lots of discussion about what to do. For those of you who do not know, the latest motor oil formulations have significantly reduced the anti-wear additive ZDDP (provides phosphorus and zinc). Per SAE papers approximately 1200 ppm of both phosphorus and zinc is needed to prevent premature wear of rotating parts like camshafts in cars that have flat tappets (like older Porsches).

Newer cars have roller tappets to help save fuel. As a side benefit, they do not require the level of ZDDP that non-roller tappets require. Until the advent of the CJ4 / SM grades now currently offered, the ZDDP Levels of quality motor oils provided the phosphorus and zinc we needed.

I am an EX-Royal Purple user -

now use Brad Penn Oil - 1/2 the price of royal purple and 1200 ppm ZDDP levels for my engine.