Oily Residue From Prop?

[Bushwacker]

If you're just running it at idle with 50:1 premix, which contains a LOT more oil than the motor needs for idle speed, yes, a lot of residual oil will build up in the exhaust passages, so it'll eventually dribble out the exhaust. The 50:1 mix is really only needed for WOT operation. When you're out on the water and running at high power, the oil gets blown out and doesn't have a chance to accumulate. What you're seeing is totally normal. If your ran through a long 30 minute idle speed zone with no subsequent high speed operation before pulling the boat out, I think you'd see the same thing.