Originally Posted by limitlessent
I guess I'm just gonna run the 87 tune on 89 gas.
Right now I'm running 87 tune on 87 gas but don't know how to check to see if it's a problem or not...
Thats what I started out with running the 87 tune on 89. The past three fill-ups I switched to the 93 octain tune and have been filling up with 93 and with each tank the truck's performance continues to improve (including mpg's).