I was running late today, but the low fuel light was on so I had to get gas.
Pulled up to Meijer and someone had just pulled into one of the E85 capable pumps, and the other one was out of service. D'oh!
I took the opportunity to fill up with 93 octane to see how the car runs on that.
First impression? No difference. The same sound the engine makes under load with E25 it made with 93 octane. Maybe it's not a pre-ignition sound like I think, could just be something else.