RE: Special oil for gas now?
There have been warnings in the ultralight airplane industries for years now about this. The theory is that the alcohol in the gas attracts moisture, (which it does), and that this water content in the fuel is what will not mix with the oil. We were warned to test gasoline for alcohol, and if it had it, not to use it.
Now, having said all that, in hundreds of hours flying two stroke powered ultralight airplanes as an instructor, and years of maintaining many ultralight airplanes, I have to say that I have never seen a problem.
Nor have I seen it with my model airplane fuel.
In a full size airplane, (ie. Cessna, Piper, etc.), some models have an STC to use auto fuel. In this case, if I were flying an airplane using auto fuel, for various reasons I would prefer a gasoline without alcohol. The STC to permit auto fuel in some models of aircraft came about because of serious lead fouling spark plug problems with aero engines that were designed to run on 80/87 octane fuel, but were forced to use 100LL when 80/87 fuel was discontinued. This lead fouling problem is also why I don't recommend AVGAS for model airplane engines.
AV8TOR