The use of ethanol blend gasoline has many more ramifications that just O rings and carb parts. The ethanol gasoline has a lower vapor pressure that straight gasoline which may give you trouble at higher altitudes above 8,000' It absorbs water and holds it suspended in your fuel. Carb icing becomes more frequent in conditions that normaly would not form carb ice if straight gas was used. Ethanol is a wonderful solvent which attacks (shorter life spans) of many rubber items(O-rings, Fuel lines) that it comes into contact with. It can also dissolve foriegn matter in your tanks and that crude can plug fuel filters. Ethanol gas has a short shelf life. With Extented storage(3-4 weeks) of ethanol gas in your tanks it will start to form acids, varnish, or the ethanol will start to seperate from the gasoline so you will have pockets of almost pure ethanol in your tank . Because of this acid and varnish formation, many chain saw, lawn mower, and garden tractor engine manufactors do not recommend using it in their engines. Ethanol has fewer BTUs per gallon that gasoline, expect a 3-5% increase in fuel comsuption at the same horsepower settings.
Overall, I can not recommend the use of ethanol blended Gasoline in aviation engines even though the state I live in, Iowa, is the largest producer of ethanol (23 plants) in the nation. Brant Hollensbe Des Moines Ia bhollensbe at mchsi.com
