captinjohn, here in part is something that was previously posted on RCU and may tie in to what you are saying.

"One of the functions of good 2 cycle engine oil is to keep the carbon somewhat softer than if there was no oil in the fuel so that it can be burned, washed or scrubbed off to some degree as the engine runs.

Bill Krueger (OMC Engine Development 30 years , retired)"

Ken