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1966 Shelby GT350/GT350H / Re: Adding zinc to a 66 G.T. 350H
« on: August 01, 2023, 07:10:17 PM »
Will never forget the 1st time I put Amsoil synthetic in my '72 351 Mach 1 in 1974. Same result - idle speed increased about 200 rpm and the engine ran a little cooler according to what I saw on the temp guage.