Here is the RULE for using alcohol based fuels. If you violate them, you will be punished by dirty, junk oil, an oil that is coming apart during use, and a mutitude of other oil related failures, that don't look like oil failures. I'm not even going into ring seal, because I don't feel like typing a complete "scientific" expose on it.
The RULE is this: never EVER use a Group IV or V synthetic base oil with alcohol. Some guys claim they run synthetic base oils but they don't. They don't know the difference between base oils. You should learn for yourself rather than take my word for it.
You CAN use (on alcohol based fuels this is what I use) a blended Group IV or V base oil with a high TBN mineral oil developed for alcohol based fuels. It's not as expensive as a real, full synthetic, but it is formulated for the more than double amount of alcohol it takes to make the same power that gasoline does.
Saying synthetic on the bottle doesn't mean a thing. The United States Supreme Court fucked that up for everyone in this country.
