I think your motor originally called for a mix ratio of 3/4 pint of oil per gallon of gasoline.
I would recommend using a TC-W3 rated oil with ethanol-free gasoline. TC-W3 is the current (3rd) standard/certification for Two Cycle Water-cooled motor oil. Gasoline with ethanol has been proven harmful and corrosive to old small engines (including outboard motors). To see the effects, there is a video on Youtube by Project Farm called Does Fuel Stabilizer Prevent Ethanol Damage? which shows what can happen.
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