After Break In Oil

mullinax95 said

I don't see why you say it is just SM rated when you plainly can see that where I copied and pasted the oil rateings off of the Rotella web page in my post that it is still SL rated also as well as SM rated. And you can click on the link and see for yourself that it is still SL rated if you still don't believe it.

Click to expand...

The zinc content went down with oil rating SJ, again with SL and even more with SM. SM was a big drop from SL. Car Craft had an article that actually listed the amounts of zinc in the various types of oil. Basically there recomendation was a good quality SM oil still has enough zinc for a flat tappet cam once the engine is broken in. The reduction is motivated by emission requirements on new cars for 100k miles. Zinc is not good for catalytic convertors.

FWIW, STP is advertised to have the highest level of zinc of all oil additives.