1998 Yama 9.9 4 stroke making oil.

1997 Yama 9.9 HP 4 stroke, making oil? Operating 7 hours gained 1/2" in reservoir smelled gas. Majority operation trolling, a lot. Problem glazed cylinders, bad rings? I used a de-carbonizer and didn't help. Did any experiance it. Thanks, Yambutt

It seems that a lot of 4 strokes make oil, the so called remedy is to run the engine hard for a while every time out to help evaporate any fuel in the sump. Reasoning being outboards are regulated to run at a much cooler operating temperature the engines in our cars-- 135 compared to 200 degrees. Trolling alone will never allow the engine oil to get warm enough to get the gas in it to evaporate off. It would seem that preventive maintenance would dictate rather more frequent oil changes. Outboard manufactures don't seem to recognise the problem.