Whatever grade the owner's manual says. If you use a lower grade than what
the manual states, you will see a drop in performance and gas mileage. As
strange as this may sound, if you use a higher grade than what the manual
states, your gas mileage will drop, it will be harder to start, and idle
will be rougher.

HTH
Gyz

I use 87 octane and it runs fine. I'm pretty sure I've read this in the
manual when I first purchased this fine vehicle :-) I have used 91
(midrange) on a couple of occasions but it didn't do anything for
performance.

Come to think about it, I think I've seen more of the new 300s than I do of
the older style ones?

I wonder where I can get this information from?

Ken