Quote:
Originally Posted by drolston
Valvoline VR-1 20W50 racing oil has the higher zinc content which is better for flat tappet cams like our flatheads. A little more expensive, but good insurance. Most auto parts places carry it.
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Extra zinc is NOT needed in a flathead! There is still sufficient zinc in modern oil for the low spring pressures of flatheads and other old engines. In the '50's, when these were just old oil burning/leaking clunkers, it was common to use re-refined oil or the cheapest non-detergent oil available. No zinc there! I have never seen a flathead with a wiped-out cam lobe in spite of this!