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Thank you ,,,,Really depends on a few variables. What type of oil, what type of gas, and what year/make motor. OMC, aka Evinrude/Johnson made some bearing changes in the 60's, going to full needle bearings in the 9.5's. I run 100:1 in my 9.5's and have been for 40 years. This is Amsoil pre-mix 100:1 outboard fully synthetic and non oxy fuel. Saber Amsoil is even better. Pre needle bearings, I run 64:1....2 oz per gallon. Still running my 65 Fisherman 6. Nearly 4000 hours on it. All original except for coils, points, condensers, head gasket, and 1 pump impeller. Been on Amsoil since 1976 mixed at 64:1. Others may argue, but it works for me....proven.
Oils were poor back in the 50's, so that's why mixing ratios were 24:1. Fuel was leaded too, that helps with lubrication and cushioning. So it goes to show how oils are so different now.