93 octane
 

I've been burning 93 octane but it being so expensive would 89 octane hurt my engine or really decrease performance on my 8

multiple threads on this already, do a search.

quick answer: try it .. if it knocks, go back up. really depends on the quality of gas in your area.

I don't get people like you OP. you buy a car that makes gas disappear like virgins on prom night. If you drive the car the way they intended it to, you get 12-15 mpg. The difference on a full tank of gas is about $2.60 from 89-93. Who cares? Buy one less burrito at taco bell and you're already ahead. You really want to risk your car and checkbook to save literally a couple bucks? Please trade in for a prius. This car is not for you...

Burn the best
 

I accidently put 87 oct in my 07 awhile back-didn't notice any difference,but I don't plan on repeating. As blazenblue63 says,the way it burns gas it makes very little difference to let it drink what it likes the best.

I use 91 octane and my car is still running fine without any major issues.