Achimpmunk,
My post only reflects what I have read. I have no first hand experience with a cam or lifter failure due to lower levels of zinc in motor oil.
The articles I read, which were authored by cam manufacturers and major oil companies stated the only area of concern for this was a brand new cam install which involved new, high pressure valve springs...a hot rod engine.
After the initial break-in period, after the lobe and lifter face wore to each other and were polished, the need for extra protection was no longer needed.
I feel safe in saying there never was a stock Stovebolt engine that came anywhere near needing a zinc rich oil.
Stuart
