Quote:
Originally Posted by 69a
VR1 is recommended because it has a high Zinc content which is beneficial for flat tappet engines. There are some on here that say we don't need it on our engines because of the low valve spring pressure. I am no expert. but I am running VR! 20W50 in a rebuilt Flathead. My oil pressure is 80psi even after 20 miles at 180deg. I think 80 is way to high! So I'm thinking 10W40 or 15W40 may be better. If you are running an oil filter (any style) I don't think detergent level will matter.
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VR-1 is available in 10W30, and is the best weight for most modified street engines.