E85 isn't really hard to find. It's just low quality, poorly regulated gas. So, be sure to buy a test kit and test it every single time before you fill it up. E85 in and of itself can be irregular, but it's more often how the station stores it and if the tanks leak or are sealed properly. E85 draws moisture out of the air and causes water to condense in the gas station fuel tank (or your gas tank if it's left for more than a few days undrained). So, you have to watch out for water deposits and E85 concentration. The two stations near me that have it, I'd never use it in any of my cars (grocery getter or otherwise). They never test consistently and one of them routinely has to shut down the pump at least 2x per month for maintenance to remove the water buildup.
In my high performance cars that were E85 converted, I only ever ordered drums from racing suppliers after I blew 2 sets of plugs in a week due to bad E85 that I got AT THE RACE TRACK.
In my high performance cars that were E85 converted, I only ever ordered drums from racing suppliers after I blew 2 sets of plugs in a week due to bad E85 that I got AT THE RACE TRACK.