Thank you all for the informative posts. I really appreciate it. I just found it surprising since I always assumed that you HAD to use 91 or above to stay in warranty. Main reason for my question was if I'm driving out somewhere remote where I get to a gas station that has run out of premium or super, if a tank of regular would kill the engine. Looks like I'd be fine in a pinch.

I really appreciate this awesome forum. Thanks folks!