Yes, I have not ran it in the lake yet, I have been running it on the motor muff. I have an Accumix fuel tank with this motor which automatically mixes the outboard oil with the gas, so your saying this is the unburned outboard oil from the fuel mixture? That makes sense, the accumix may very well put a little more oil in the gas than hand mixing which may result in more unburned oil than normal. I am told that 2cycle engines only burn about 50% of the fuel anyways and pump the rest into the water, is that true? By the way did you look at the picture of the motor I attached? Thanjs a bunch, I will check the lower unit oil, it needs to be changed anyways.