07 Denali fuel grade

BR DENALI · February 28, 2007

Just purchased a new Denali and was wondering about which grade fuel to use. It seems every magazine article you find says premium is recommended but you can use 87 octane regular. My question is the owners manual states regular fuel with a minium octane of 87. So exactly where is the GM recommendation to use premium? If the truck will make its rated performance figures with quality regular fuel running premium is pointless and a waste of money. It would be great if someone can point me in the right direction for a source of the GM recommendation. Thanks.

C & A s Dad · February 28, 2007

I cannot point you to the GM requirements but I can tell you my experience and you will find that many here will agree.

Your truck will run and perform better and will likely get better MPG with Premium. I run 93 oct only in my 02 Yukon XL, which "requires" a minimum oct rating of 87. I think the key word here is "minimum" I did this after several recommendations form members on this forum and because I was towing a camper. Your engine has a moderate to high compression ratio and the predetonation or "Ping" is controled by a knock sensor and the computer. When the sensor detects knock, it tells the computer and it retards your timing to make it go away. It will then very slowly increase timing until the sensor hears knock again and once again, it retards the timing. With premium fuel the knock or ping may still occur but it will allow the engine to run a much higher degree of timing before it does ping. This will provide you with better performance and in my case better MPG. I am averaging 18.6 MPG out of a Yukon XL with a 4.10 gear. This is mostly rural driving with very little pure highway driving. It will get over 20 with only highway driving. I cannot say the Premium is the only contributor as I also run syn fluids front to rear, maintain 37 PSI in my tires, have a True Flow Intake tube, and my wife is a conservative driver.

With all of that said, you can likely run 87 oct and will not experience "poor performance". You just will not be getting all your truck has to offer. Kind of like buying Michelob or Milwaukee's Best, they will both get the job done but one is so much smoother.

Lerenis · March 1, 2007

I think "C" hit it on the head in regards to fuel grade. Most people wouldn't feel or hear the difference betweent he different octane's available today. While I don't get the 18 mpg, I do average around 14mpg and I have a lead foot. I have the shorty Denali and with the weight difference compared to the XL it literally flies completely stock. The 87 minimum is fine but the engine seems to respond better with the 93 in it.

On a different note, I did notice that the idle to be a little higher pitched using the lower octane. I filled the truck up about three times with 87 and noticed in the morning, when I would remote start it, that it seemed to run a little louder and it would seem the same way at lights etc... Changing back to 93 the idle is more of deeper rumble and sounds like it enjoys it better. I seem to get a few more miles per tank versus using the lower octane. Just my two cents worth. Enjoy your new truck!

Fyrcaptain · March 1, 2007

If it were a "requirement" versus a "recommendation", it would be noted on the fuel guage and / or inside the fuel fill door as is on several hi-performance vehicles that were designed to run only on premium.

Mine's got 175 miles on the clock with the same tank of fuel that the dealer put in it. They buy the cheapest 87 they can for their dealership tank, and that's what they filled it with.

DIC says 13.6 so far for around town only miles for the 30 miles I have put on it.

I'll try premium next load to see what the difference is, although during break-in and prior to Mobil1 at the first oil change, it will be a moving target.

C & A s Dad · March 1, 2007

I failed to mention that when I received this advise, everyone told me that you cannot judge your power or MPG improvements from a tank or two. I am not Technician but what the Techs on this forum said was that the computer retards the timing in miliseconds when knock is indicated but it takes it much longer to bring the timing back up. Try a few tanks of premium before you make up your mind if it is worth it or not.

BTW, On a different note with the same subject, I am a believer in name brand fuels and I use Chevron exclusively in my presonal truck and most of the time in my company van. I also have not issue with Texaco because it contains Techron as with Chevron. Of course there are other name brand quality fuels out there. Some will disagree but many do agree that their is a difference in a Top Tier fuel.

BR DENALI · March 1, 2007

I failed to mention that when I received this advise, everyone told me that you cannot judge your power or MPG improvements from a tank or two. I am not Technician but what the Techs on this forum said was that the computer retards the timing in miliseconds when knock is indicated but it takes it much longer to bring the timing back up. Try a few tanks of premium before you make up your mind if it is worth it or not.

BTW, On a different note with the same subject, I am a believer in name brand fuels and I use Chevron exclusively in my presonal truck and most of the time in my company van. I also have not issue with Texaco because it contains Techron as with Chevron. Of course there are other name brand quality fuels out there. Some will disagree but many do agree that their is a difference in a Top Tier fuel.

I use only top quality fuel as well. Mostly Chevron but will use most any TOP TIER fuel. For those that don't know TOP TIER is a standard a number of auto makers published that exceeds the government requirements for detergents and other additives. GM is one of the auto makers that developed the standard. To a great extent you do get what you pay for. I did a search on line yesterday and found in a GM Media press kit for Canada that Premium is recommended but 87 octane is usable. Most magazines only regurgitate what they've been told so I suspect it is buried in a data package they all get when they evaluate vehicles. Seems GM is trying to avoid coming out in print in our manuals that our fuel guzzling trucks really should use the most expensive fuel. Sneaky buggers. Oh well, every other vehicle I own needs premium so life marches on as normal. Just thought I might catch a break. Premium it is! Thanks for the input.

Lerenis · March 1, 2007

I also tend to stick with the major brands. I don't use "Benny's Gas" so to speak unless I am forced to walk. The worst part of always using the premium is you usually get a hose full of the regular grade at the start.

Cheers!

cmoore74 · March 1, 2007

I agree with C & A s Dad. I gave 93 octane a try and here are my observations:

- Almost a 1 MPG increase in mileage

- A little better increase when towing my boat, about 1.5 MPG

- Engine seems to run smoother

The increase is not huge, but it's about enough to offset the increased cost of 93 octane.

If you base the requirements on the compression ratio of the engine (5.3L) then it would call for 92+ octane. You can run 87, but the computer will retard the timing to avoid knock. This is what results in the engine running less efficiently.

GM would not say you have to run premium as this would turn a lot of peole off from buying the truck.

Give it a try and tell us what your results are.

Also it does take a few tanks to see a difference as the computer has to adjust for the fuel so trying 1 tank may result in no oberservable difference.

Oh, and top tier fuel all the way. In my area this is Shell.

svensk · March 1, 2007

I use Conoco or Exxon here in MN. Both have top tier additives I believe as well.

Right now I use 87 for the winter because the winter grade gas is crap to begin with. It's so loaded with junk that I'm getting literally 13mpg right now. Granted I need new O2 sensors but this is ridiculous. I can't wait for spring when the regular gas comes back my milage will skyrocket back to 16mpg.

MotoMedic · March 29, 2007

funny thing... about a year ago, saw a gas truck filling the tanks @ a Chevron station. after he finished, he drove across the street to an Albertson's Supermarket gas station & began filling their tanks. had to find out the deal, so i went & asked him. he said chain stores buy from different gas companies & just so happens my albertson's buys chevron. found me a sweet way to save a little cash on good gas!

(you may ask how i witnessed all this- i used to work on the ambulance & we often got posted on street corners for hours in between calls)

ken1mod · March 29, 2007

In my fleet management days, we used cheapest fuels available. Perfectly clean engines and no problems ever. No seafoam or additives of any kind ever. Run 'em hard and change oil every 6k with good quality dino. Engines only damaged through overheat, blown rad hoses, etc and drivers that didn't stop. Mostly small and big block chevys. Ford 460 did blow up for no good reason though. Oil pump failure?

Ken

cerbomark · March 29, 2007

I hate to be the devils advocate but,, from what I ve learned, if a motors compression is designed and made to run on 87 octane, a higher octane will have no benifit and may even use more fuel. I m not talking about a motor like the LQ9(SS) which CAN run on lower ocatan by reducing the timing. I m saying a motor like my 07/ 6.0 which I assume is made for the lower octane.I read you can cause more carbon buildup by using a higher ocatne than called for cause the motor doesn t burn it all properly. Not sure what the Dennali has. You may have the same motor as my v max... Just my 2 cents, alot of info on the net if you do a search.

GeoHawk · March 29, 2007

I hate to be the devils advocate but,, from what I ve learned, if a motors compression is designed and made to run on 87 octane, a higher octane will have no benifit and may even use more fuel. I m not talking about a motor like the LQ9(SS) which CAN run on lower ocatan by reducing the timing. I m saying a motor like my 07/ 6.0 which I assume is made for the lower octane.I read you can cause more carbon buildup by using a higher ocatne than called for cause the motor doesn t burn it all properly. Not sure what the Dennali has. You may have the same motor as my v max... Just my 2 cents, alot of info on the net if you do a search.

I've heard the same thing about using unnecessarilly high octane fuel: no power/fuel mileage benefit, wasting $, etc.

Our VortecMax engines aren't the same as the Denali motor, though:

VortecMax (L76) - 6.0L, 9.7:1 compression ratio

Denali motor (L92) - 6.2L, 10.5:1 c.r.

There are some other differences too, like the L92 has a little more agressive cam as well, but it would appear that the L76 is designed for 87 octane while the L92 is designed for 91-93 octane. Using 87 won't hurt the L92, but the ecm will retard the engine timing to prevent knocking, thus reducing the power output.

tobias · March 29, 2007

Not sure if the 'Nalis are Flex Fuel ready, although for that much they d**n well ought to be, but if they are, run E85. It's 105 octane so your HP and Torque numbers should be higher and your engine should stay much cleaner. Not to mention the help you'll be giving to the environment. Now, you will lose a little MPG but if you can afford a Denali, do you really care?

Daddy.