Will E85 corrode my fuel system? No, for corrosion to develop high levels of moisture are required. E85 is produced from dry-milled ethanol, which contains less than 0.5% moisture, which is required by law based on ASTM E85 fuel standard. Corrosion requires minimum moisture levels of at least 4% or greater. It is not the corrosive properties of ethanol that can cause damage to your vehicle; it is the water which can rust a vehicles fuel system from the inside out. Todays vehicles (since mid 1980s) have fuel systems which are made to withstand corrosive motor fuels and rust from water. Because most states have gone to E10 or gasohol, we no longer experience moisture buildup in fuel delivery systems.
This is where one has to be careful. Ethanol is produced "dry", but during piping, storage, pumping, and even in your tank it can draw moisture at a much greater rate than gasoline. The higher the ethanol content, the greater the moisture gathering potential. That moisture then kick starts the corrosion process. Extra care must be taken, especially if running parts not designed for ethanol use.
