Reply To: ’57 Evinrude 7.5 fleetwin fuel mix

[David Stanton]

I mix 20 to 1 using today’s TCW3 oil in all 16 to 1 and 24 to 1 motors. Yeah, I know I should use a bit more in the 16 to 1 motors, but it’s a convenience thing; mixing a quart of oil to 5 gallons of gas (20 to 1), and not having to keep both 16 to 1 and 24 to 1 cans of gas around…….but……I don’t have a 16 to 1 motor that I run very often, so only running a gallon or so a year, the motors aren’t going to wear out any time soon. If I used one of these motors a lot, including my 7-1/2s, I’d go with 16 to 1. I also use 50 to 1 in 50 to 1 motors, and 50 to 1 in 100 to 1 motors. Some of the early 100 to 1 motors led short lives. When I put a motor on my grandson’s hydroplane (anywhere form 6 to 15 HP), I double the oil because these motors rev to RPMs they weren’t designed to run at. On the hydroplane I sometimes have to go one heat range colder on the spark plugs too.

Nobody ever killed a motor by using too much oil, and I’m amazed that my PO-15 Johnson at it’s recommended 8 to 1 doesn’t smoke a lot. Racing versions of the Champion “Hotrod” motors use 4 to 1.

Dave