Originally Posted by EFI Logics
Depending on your location the way they rate octane is actually different. You likely wouldn't harm anything in your car by running a low mixture and may boost your detonation resistance a bit, but you can give it a try and log your car to make sure. Yes, E85's high ethanol content it is bad for seals over time, but if you are running a low mixture with pump gas it shouldn't be too bad. Over an extended time of continuously utilizing it you may notice it effect the car though.
Thanks. Really useful info. Interesting topic.