extuner

In phx arizona we can only get 91 octane at the pumps and our summers reach 115 degrees. I am using Shell premium or Mobil, does anyone have info on best gas for my temperature climate or, what gas in 91 octane works for you? Thanks for the input/

VWILLO

If your car isn't tuned for a higher octane fuel, you should just use a quality 87 octane and save for a custom tune.

extuner

I have 07 auto, fuego 91 tune and gms cai and because of the modsI am asking what fuel is preferred/ Of course I could enter the 87 tune and I would wonder if there is a brand preference there too. Thanks/

Orion_240

sorry but in my experience, if you're using brand name gas like Exxon/Mobil, Chevron, 76, Shell, Arco, etc than the only way to tell is getting an octane testing kit and finding out which gas is accurate. I would use whatever station seems the most trustworthy or even better see if you can find a small independent station that carries high octane gas. We used to have a small station nearby that sold 93 but developers closed it.
As far as when I'm traveling I use any of the above except for Arco, as I don't want the hassle of having to go inside and wait in line to pay cash.

mygt500

Get a custom tune for the 91 other than that no point in running any more than 87 octane

UrS4

I think BP, Shell, Chevron, Mobil are all fine.

The only thing I pay attention to is if there is any ethanol added. If there is ethanol, I just find another station because numerous members have said that tuned cars don't like it.