John Burchfield
PCS Life Member
A few months ago I was down at the barn preparing to change the oil in my '69 M-M and drive it home. I called Gene Smith about something else and he mentioned that I'd better check to see if my Havoline 30wt had the appropriate additives. Apparently as these SAE service designations for motor oil have advanced, some additive(s) crucial for older engines have been left out of many brands of oil. Gene had researched this a while back but couldn't remember the details. I think he said he'd switched to Mobil One for his ambulances. The crucial additive is a three or four letter acronym. I know I may be repeating a previously asked question, but this is something pretty important to all of us, as using a "too modern" motor oil will apparently cause premature valvetrain wear. I know that by 1972 or '73 the manufacturers knew that unleaded gas was on the way and "low lead" gasoline began appearing around then. What was the break point for when this crucial additive was needed? The end of the high compression engines was the 1971 model year, and catalytic converters showed up nearly across the board in 1975 so I'm wondering if mid 70s and up models might be OK w/ modern oils? Thanks for your help!