I don't know about the fuel separation issue, so I cannot comment on it. I've read stories taking both sides of the issue - gasahol will separate and it does not. Maybe a chemical engineer will settle this once and for all for us.So a question that popped in my mind. My wife has a Prius. She gets 55-65 mpg and it takes her at least a month to get low enough to stop for gas. What kind of unintended consequences will happen to people who don't refuel often like her?
Or leaving your car in the garage cause using your bike during the summer months...What kind of unintended consequences will happen to people who don't refuel often like her?
I have found this to be true with the ST, 87-93 octane about 40 mpg, ethanol free about 10% better gas milage, makes me shake my head that I use "more" gas, when I thought it was designed to use less. I have not tried 15%, hopefully I won't be in a situation that requires it.The bigger concern (for me) is; although I have two vehicles that are capable of E15, I do not use it. On a road trip I did try the E15 and found I had approximately 10% less efficiency (which, at the time, negated any cost savings). Conversely, I had approximately a 10% gain in mileage with "pure" gas, which almost (but not quite) paid for the increase in price.
In my experience, although your fuel bill will be a little cheaper at the pump, you will be returning more frequently as your overall mileage will decrease.
Disclaimer; this may not be the case for newer vehicles that have more focus on E15 from start of design. I have a 2016 Ford Transit and a 2016 Highlander that I tried this on and they can use E15 but I think they are not optimized for it.
Ryan