I still have about 8 quarts of Red Line 5wt, Racing Oil in my stash, compliments of a glitch on Amazon. I've used 4 quarts, in the past OCI's, to thin out some 15w50 M1, full synthetic. I ran a blend of 4 quarts of M1, 15w50 with 2 quarts of the Red Line 5wt in my Toyota 4Runner SR5 V6 for 9-10k...