I filled up with 87 the other day just to see the difference in performance, mpg, etc. and I found that there is a difference from 93 (my usual grade).

First, my MPG was down from 17.7 average to 15.8 while generally following thesame roads. The other difference I noticed was more sluggishness in acceleration. I didn't notice any knocking or any otherissues.

I of course will stick to my usual grade but it was an worthwhile test just from a curiosity perspective.