E85 fuel is a strange beast, it is 85% ethanol and 15% gasoline. This creates two unique problems; (if you don't want the read all the science, the bottom line is add Valvoline Water Remover and Gumout for flex fuel several times a year and your good to go)

Ethanol is hygroscopic (loves to absorb water) but when combined with 15% gasoline, the water will drop out of the ethanol at only 0.5% concentration. What that means is, in the morning when it's cool with high humidity the E85 is sucking water out of the air, then letting it drop out of solution and settle in the bottom of your tank. Fortunately there is a very easy solution; once or twice a year add a water remover that has isopropyl alcohol base like Valvoline Water Remover. The brand isn't important, what you need is isopropyl alcohol based additive. Rubbing alcohol will work, but you will need to add a lot of it, because it contains 30% water to keep it from evaporating too fast when your Honey rubs it on your back .

The second unique problem is, the 15% gas in E85 has detergent added to it, one of which is Poly Iso-Butylene. It is a excellent detergent in gasoline, but it SUCKS when it is in a 50% or greater solution of ethanol. For some complex reasons, it actually becomes insoluble and plates out on injectors and valves. The EPA has know this since 2007, but has not changed the rules that force gas companies to add it to ALL gasoline (except racing fuel). GM and Ford have both tested E85 engines and found that in normal in-town driving the fouling can become significant in as little as 5,000 miles. At highway speeds the fouling slows significantly, to the point that it is a non-issue. Again, there is an easy solution; use an injector cleaner that is formulated for flex fuel and contains methylal. I only know of one, Gumout for flex fuel. There may be others, I just don't know of them.

I hope this helps. Just for the record I don't own stock in either Gumout or Valvoline, although I may have to get some now ha ha ha.

I don't use E85, I use Shell 93 octane. I did all this research for 2 friends (Ilonggo and Necrotic Brain) who did the conversion. I'm a retired Chem. E. that happens to live close to one of the only colleges that offers a Petroleum Engineering degree, that's how I got the info for those guys. They asked me to post the info., so I did.

So, now you know, I have no first hand knowledge running E85. I did find out that the injector fouling occurs mostly when you are doing in-town driving, not at higher RPM. Also, running the tank near empty (not gauge empty, real fuel tank empty), run 2 tanks of Shell through, then run near empty and go back to E85, your injectors will be clean. I was told that doing this every 6 to 8,000 miles would not only clean the injectors, but the "sludge" that can build up in the fuel tank, without plugging filters. Using this approach, both friends cars run like bats out of hell (Ilonggo has run 9's at the drag strip).

If you do mostly highway driving, don't worry about it. Maybe once every 15 to 20,000 miles, run a couple of tanks of Shell through and you are good to go. Never add gas to a tank that has E85 if you can avoid it, the sludge build up in your tank will be much worst (read get ready to change filters).

Last point; advice is rarely worth more than you paid for it. All this info is from talking to professors, no actual experience.

Dimethoxymethane, also called methylal, is a colorless flammable liquid with a low boiling point, low viscosity and excellent dissolving power.