Here we go again with a lot of opinions on the subject. I would run 16 to 1, but that’s another can of mixed gas to have around. I use today’s TCW3 rated outboard oil (I think it’s all rated TCW3 now) and for my 24 to 1 and 16 to 1 motors, I mix it at 20 to 1. It’s easy to just dump a quart into a 5 gallon can of gas for 20 1o 1. When your motor was new, your 5.5 (I’m assuming Johnson or Evinrude) also said if you don’t have outboard oil, use SAE 30 weight, non-detergent motor oil, so I figure with today’s better oil, I can get by with 20 to 1. When I put a small motor like that on a hydroplane for my grandkids to run, I double the oil mix to 10 to 1 because the motor runs at a higher RPM than it was designed for on a light little boat like that. So that’s my 2 HP on the subject! No way I’d run 32 to 1.
When you say it runs “too rich” on 24 to 1, what do you mean? What are the symptoms? Your high and low speed carb knobs adjust the lean/rich mixture for optimum performance mixture regardless of the amount of oil – adjust the low speed knob with the motor in gear with it idleing. Adjust the high speed knob with the motor on a boat at wide open throttle for max speed – you can hear the difference. If your spark plugs are fouling with black or wet oily deposits, try a hotter heat range plug. Heat range is all about the temp of the spark plug tip to keep plugs clean. If you are running Champion J6J plugs that need frequent cleaning, try J8J plugs.
Dave
