First time in Utah went to a gas station and just choose the lowest octane rating fuel I saw... was obviously a 85 and I first panicked till I read on the internet that the worst that can happen with newer cars is lower performance or worse mpg. As I'm currently driving on the I-80 E from Salt Lake City I just wanna share my experiences with it...
So far I didn't had any problems with it, neither performance issue nor MPG which is still at 41.4. It's good to know that after Evanston I was never lower than 6000 feet again, I don't know how the engine would handle it when I would drive around in lower altitude.
For now I'm happy that the engine runs smoothly and I'm definitely gonna pay attention and get 87 again.
PS: I'm driving a Nissan Altima