Gas difference?

My point was if it's supposed to run 87 it's well within the realm of reasonable behavior to require one stage higher octane in the summer months. Not sure what the bit about the ecu correcting out higher octane fuel is but I don't think it's accurate. It's a pretty basic computer.

 

If i had to guess its an extension of the placebo effect. People go high octane amnd "feel" the difference but after a while it feels normal. In reality the high octane did exactly 0 to start with. An engine will always advance as far in its range as it can, its not going to return back to "normal" because it got used to anything..

 

Yes, higher octane has more pre detonation resistance, so as soon as you fill up you may notice the ping is gone. Within a few miles, however, the ping will come back. At least this was the case for me.