Quote:
Originally Posted by Step'67
This. The non-synthetic oil recommendation generally isn't due to lack of zinc/phosphorus (which most oils today, including conventional, do indeed lack and is necessary in flat-tappet engines), but the detergents in synthetic oil are supposed to cause issues with the rings seating and other mating surfaces getting to know one another.
Just a couple weeks ago, my cam wiped a lobe after several years of zero issues despite running one of Amzoil's high-zinc formulations. For the new cam and lifters break-in, I ran Valvoline VR1 SAE 30 which is a non-street legal, high-zinc race oil, plus some zinc additive. Brad Penn's break-in oil also carries a high recommendation. A dedicated break-in oil like Penn's or Amzoil's (what I used for the first build) in my mind would be better as break-in additives can degrade/interfere with the base oil's additive package. Though I do know people have had good luck with GM's EOS as '68OS recommended.
I will be stepping up to Amzoil's ZRod formulation that has a higher zinc content for the remainder of my engine's life instead of their standard high-zinc line. Just be sure to run a high-quality, high zinc/phosphorus oil for the engine's life, not just during break-in.
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Forty years ago, that was the break-in formula for the first 500 miles. It worked then. These engines are the same, so it should work now. That engine ran 250,000 miles from 1977 to 2002. At which time I rebuilt another one using the same kinda stuff. I also ran it on Valvoline SAE 30 Racing oil, gradually going to 40 weight, 50 weight, by that time it was time to rebuild. I changed oil at 2000 mile intervals.
The ''new'' engine I run on Valvoline VR1 SAE 30 Weight Racing Oil, as well, but sometimes 20W-50 in the winter. I live in Arizona.
Step'67: what caused the lobe wiping of your cam?