Summit Racing oil

70Duster340 said

So, an oil that's already containing zinc is good, and additives are bad? Is there oil on the market that may have too much zinc?

Not trying to be a smarta**, just attempting to gain some knowledge.

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You have to get a data sheet from the oil manufacturer on the grade you're using and then compare it to the minimum requirement of zinc ppm. I remember something like 1500.
I'm more about its viscosity breakdown with temp. Most thin or cheap crap loses 20 psi.