[RocktimusPryme]

Originally Posted by locomotivebreath

I have a quart of valvoline HD 40wt from 1970 that I’m thinking about sending off to blackstone and see just what the ZDDP was back then .

Please do, I would love to know.

Im a firm believer that oil zinc levels gets blamed a lot for cam wipes and lifter failures, when the reality is people run too much valve spring more often than not. Not that lubrication is never the culprit, I just don't think its quite as important AFTER a cam is broken in and work hardned as it is sometimes made out to be. Break in is a different story.