hello i am looking to buy an H2 with in the next month or so. what grade of gas can you put in an H2 my father has had an 01 gmc denali and an 03 escalade when he bought both vechicles the sales managers told him he can put 87 grade gas in bothtrucks. so i was wonderingif anyone has put in the lowest grade in there hummer h2 and how has the performance been. thanks

 

I believe the manual says 87 octane is fine. That is all I have used in mine.

 

it's designed to run on 87 octane. the only valid reason for using a higher octane gas would be if you have a supercharger.

 

or if you just feel like spending more cash

 

I think I read that the '08's are supposed to run on Premium, but, yeah, 87 for '03-'07!!

 

All I ever put in mine was 87 and no issues at all. It ran perfectly.

 

Hi, new to the forum, but I just got done discussing this subject with a friendso I will throw in my .02. I get 14-16 MPG on my 2003 H2 (highway @ around 70 MPH) when I use premium gas. I tried using 87 and got 11-12 MPG.This was a big enough difference to justify the extra .20 for 93 IMO. After I figured it out i came out with an extra 30 or so miles per tank gained. My Cadillac is also ok to run regular gas, but gets 18 MPG averageV.S. 24 MPG averagewith premium. I have tried the test more than once and consistanly get enough extra miles out of a tank of gas with my cars to justify premium. I don't know why that is though...Neither car runs any differently with regular/premium gas, they just get worse MPG.

Lisa

 

shouldnt be getting better gas mileage, might indicate a problem with your engine...octane level has nothing to do with gas mileage, its all lined up on compression

 

I hear you guinessboy, but I have three high end vehicles and I have done this little experiment with all of them. They all get better MPG on premium. I wouldn't keep trying the regular and doing the math if I wanted to pay for premium. It does indeed seem to make a difference. why don't some of you try it and let us know if it matters. You have to run a full tank of regular and keep track on paper of the gas mileage. The fuel economy average guage doesn't always reflect correctly in my experience. I just had my whole guage cluster replaced under warranty, LOL! Then run a whole tank of premium and keep track on paper. Then you have to check the cost of the cost of the premium over the regular and figure out if you benefit. If you put 10 gallons of premium in it would cost 2 dollars more. So if you got 3 MPG better then you would get 30 more miles out of the 10 gallons. The $2 you spent wouldn't have gotten you a whole gallon so maybe you could have gone 9 miles (i am being generous here). Net profit on 30 galloms would be 21 miles extra. That is of course if you saw a difference. ...

Sorry for any typos, I am typing this on my phone.

Lisa

 

if its working for you then by all means i would keep doing it......i just did some internet research on gas and octane and every article i read said octane will not increase gas mileage and in some cases running too high of an octane can actually effect your valves because the combustion temperature rises causing valve wear. I had an srt 10 truck with a viper engine before the hummer which required high octane fuel, i was stuck in arizona at a gas station that only had 87, so i filled a quarter tank of 87 just to get me too the next gas station in the middle of nowhere and i got better mileage with the 87...just very odd, but im not doubting you at all