I just started using Schaeffer's Racing Oil, Supreme 7000, Synthetic Plus, their item #709 (1 gal. size), 10W-30, with extra Zinc additives...On their Technical Data info #709, the Zinc content is listed to be 1700 - 2300 P.P.M. I don't know if other oil manufactures give any factual info on their Zinc content.... Schaeffer Mfg. Co., St. Louis Mo. 63104 .... 1-800-325-9962 ....
www.schaefferoil.com , made in the U.S.A.... "and in my opinion, I think we have a winner"....