Hi Aeronut; Since gasoline produces more heat than alcohol, you need a larger percentage of oil for converted glow engines than for engines designed to run on gasoline, such as the weed-wacker derivitives, partly because, as you mentioned, the latter have roller bearings on the rod end, while glow engines have plain bearings, with the Aluminum rod turning against a steel crankpin. (Larger glow engines have a bronze bearing inserted in the rod).

Also, engines designed to run on gasoline are made heavier than glow engines, with more metal and larger fins for cooling. Be sure to allow plenty of airflow past a glow engine running on gasoline. If it's cowled, the air exit should be at least twice the area of the inlet, and three times as large is better.

We found that "regular" pump gas or Coleman stove fuel ("white" gasoline) mixed with 10 - 12% "Red Line" brand motorcycle racing oil worked best. We tried Klotz and other oils, but Red Line would leave a piston absolutely clean after four or five hours running. You can't do that with castor oil!

W8YE; That's a real pretty Aeronca "Champ" in your avetar. Is it full-scale, or smaller? I flew one of them when it was brand new. Can you guess what year that was?