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NESD | I have a question about synthetic oils which has to do with the reduction/elimination of zinc from all oils due to EPA regs, I have asked this question on a car forum that I am on also and nobody can find the answer, I am running Royal Purple 10-30 in my 70 mustang which is a flat tappet cam engine, do I need to add ZDDP to the oil to protect the camshaft. I have been told the AMSOIL still has Zinc in some of the oils as do others, The Royal Purple has a SL Classification which says for 2004 and older vehicles. So do I or don't I need to add the Zinc additive. The only thing I have found was not to use a SM classification oil in the older flat tappet engines. | |
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Synthetic motor oil switch question
