[38 coupe]

I find the ZDDP excitement of the last few years confusing. The stuff was added to oil in 1958. Flat tappet cam wear is very much a concern with high revving overhead valve V8s with a lot of spring pressure. Flat tappet cam wear was never a concern with a lightweight flathead valve system. I don't use ZDDP addative in any of my old Fords, including my 53 with the overhead valve 215 six (the 215 is low revving with light spring pressures). I have driven tens of thousands of miles, many at 70 mph or faster, with no camshaft or lifter problems. Any of us flathead era folks don't need to worry about it, except maybe the few Bonneville racing masters among us.