Engines are tuned for a certain octane fuel. You can run other fuels, but it won't run as well. You can tune a guitar a half step low, but when you try to play with the band, it's not going to sound right if the rest of the band is tuned standard.

I had the opposite problem years ago with a Chevy Blazer. I thought putting higher octane in it was taking better care of it, but I was having issues with bad acceleration, took it to a garage, and the mechanic asked if I had been putting cheap gas in it. I told him that I'd been running 91 and he said that was my problem. The engine was tuned for 88/89 octane. I started putting the cheap stuff in and didn't have any more problems.

__________________

• 2008 X5 3.0si Alpine White