Fuel Octane
 

Can you use the higher octane (above 87) fuel in the 6.2 and would it increase the performance?

You can use higher octane fuel in the 6.2L or any engine. I doubt you'll see much difference if any in performance, especially without an aftermarket programmer.

^^^^ yep, save your money

Expect a 10-15hp increase on 91 or greater octane (without a tuner). Whether you can "feel" this or not could be up for debate, but you will see an increase in HP. This is in the "ask the engineer" thread for reference.

You can even put E85 flex fuel in it. I don't recommend it though, I did one fill up and the mileage dropped off 3-4 mpg!! Though it's less expensive than gas you will be filling up more frequent. If I was really concerned with our air quality and saving the earth I would have bought a Prius.

I know it's going to hurt the mileage but I just have to give it a try someday after I get a few more miles on the clock.

Denny

Try it out, I did not feel any difference in performance. The overall cost is pretty much a wash compared to gas with the lower price/lower mpg's of E85. No need to constantly be at the pump IMO.

Yep, I read the same in the engineer thread, and I agree with silverbullet, since the 6.2L is a flex fuel engine the computer can certainly make some adjustments to accommodate higher fuel octane, otherwise you would not be able to put either fuel in without making any changes. I do notice quite a performance improvement on E85 though, which is supposed to be over 100 octane, something like 105, and some even higher, but its not much less expensive then gas yet way worse on gas mileage.

We are 2300 miles into our vacation and are now in Tennessee and I went from running 87 when we left Canada to running 93 octane down here and I will say that you can feel the difference in power hauling our 8500 lb 34 ft travel trailer. I have been running in manual mode and have very rarely had to go below 4th gear to maintain 60mph and the lowest was 3rd. We are in Pigeon Forge for a few days and it pulled all the hills at 60+ around here. So I say it sure does make a difference and the engine even feels better.

How does it affect your mileage? I realize that it might be hard to tell when towing over varying terrain, but just curious.

I have always towed with 93 octane fuel. It's an old habit from the days of my old 95 5.8L. If I tried to tow with 87 or even 89 octane it sounded like a thousand little men beating on anvils with little hammers in the engine any time I hit even a slight grade. I've seen what detonation can do and what a platinum plug electrode does to a cylinder from detonation. I can say that when towing it makes a difference. I don't notice much difference running 93 octane over 87 octane while dead heading.