This is what I've understood to be true since synthetics oils came out. Personally I don't run synthetics on any older engine that wasn't designed for them to begin with. If you're looking for peace of mind, just know that the conventional oils we have today are significantly better than yesterday's oils. It's true, most of them have done away with zinc, but you can still find oils with it, or you can add a bottle of zinc additive if you have a flat tappet camshaft.
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