What type of gas are you guys using? I was just at Detroit Auto show and talked to Nissan and Infinity folks. They both said exactly the same thing (regarding Maxima and G35 respectively) regarding type of gas: "Regular unleded is fine, premium recommended. But once you start using either, don't switch!" Does anybody know why don't switch???

 

I have no idea why you shouldn't switch, but I have run regular since I got the car, except over a few weeks when I was testing to see if I got better gas mileage on Super. The test was pretty much a wash, and my butt dyno couldn't tell the difference so I am sticking with regular.

If I hear a ping, I will go up to Super. There are a handful of threads on this somewhere, and all of the research I did said that you only use a higher octane in your car pings at a lower octane. Essentially, pinging means that the fuel isn't firing at the proper time.

 

The knock sensor and timing control will retard timing if you're running lower octane fuel and also reduce performance slightly. So you can run whatever you want, but you'll get the best mileage/performance on premium fuel.

 

That is essentially what I have found. If there is a difference in mileage you can't measure it with an odometer and calculator. 91 and 93 should have the same BTU potential and should yield the same mileage.

SteVTEC is right, by using 91 we may make less power under certain circumstances. I agree with you though, the butt dyno can't detect the difference, if any.