I believe anything up to and including GL-4 doesn’t have sulphur added. At least that’s what my research has revealed. GL-4 is more heavy duty than lower numbers and isn’t too hard to find.


Kevin
1951 Chevy 3100 work truck
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1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car)
Busting rust since the mid-60's
If you're smart enough to take it apart, you darn well better be smart enough to put it back together.