Best article I have seen for reasons to use only oil with high zinc levels for classic cars, which are not good for modern vehicle catalytic converters.
https://www.hagerty.com/articles-vid...07/Classic-Oil
Also seems the Indiana Region of the Classic Car Club has helped production of a special blend of high zinc oil.
http://www.classiccarmotoroil.com/
Most modern oil levels of zinc (zddp) are now near 800 ppm, due to concerns with catalytic converters. However, classic engines need zddp at levels higher levels.Test results for zddp level on oils indicated below:
Brad Penn Grade-1 oil "Greenie" 1500ppm zddp
Classic Car Motor Oil 1500ppm zddp
Castrol Edge 5w-50 syn 1300ppm zddp
Kendal GT Platinum 20w-50 1200ppm zddp
Valvoline VR1 Race Oil avail in std dino and full syn has 1400ppm zddp
Chevron Delo std dino 15w-40 1300ppm zddp
Shell rotella 5w-40 syn diesel oil 1300ppm
Mobil-1 Nascar approved 15w-50 syn 1300ppm zddp
So, I order and use the Brad Penn, but will now look for other local options.
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