When was actually the last year regular motor oils stopped having zinc ?
I have used multigrade oils on my daily late 235 from 1995 until I switched to Rotella SAE 30 last year.
I got hydraulic lifters and never had any cam issues.
It seems the danger with cam failure is more about the break-in period.
Can anybody describe what happens during break-in without zinc in the oil that causes cams to eventually fail?
