Most of you guys probably already know this but for those who don't:

Newer isn't necessarily better. Modern oils are now formulated with reduced zinc so as to avoid damage to catalytic converters on new cars. The problem is, zinc has unparalleled anti-friction properties and is absolutely required for flat tappet camshafts in older vehicles. Two ways I get zinc into my old truck:

1) Buy Quaker State Defy motor oil. Made for older engines, it is high in zinc. Available at Autozone and Walmart.

2) If I must use modern oil, I add a supplement such as STP Oil Treatment with ZDDP (zinc). Available everywhere.

3) Lots of guys were using Delo diesel oil, but I believe zinc has been reduced in that now too. Please update if you know more.

Last edited by Jay Zed; 12/09/2016 9:13 AM.