Just got an article on the E15 ethanol blended gasoline. It advised not to use it in vehicles built prior to 2012. Older cars can receive damage to fuel systems due to the separation from the alcohol and gasoline.
The bottom of the tank will be highly corrosive and the top of the tank will be gasoline of a lower octane level and can cause pre ignition.
Guess this won’t happen in newer vehicles.
We shouldn’t have a problem here in California with the separation because our roads are so bad that our fuel will always be agitated ... just like our drivers.