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Chevy Silverado and GMC Sierra Duramax Fuel Mileage



  • sullyaksullyak Posts: 30
    I am averaging 17mpg empty with mostly highway driving on my 2500 crew cab with 2,000 miles on it. I get 20+ if I keep it consistently at 65 mph.
  • coontie57coontie57 Posts: 128
    My 06 now has about 13000 on it after 11 months. Back a thousand or so miles I noted an increase in mileage. It must be getting broken in now. Pulling my 11.5K lb camper its up over 11.6 now. I have not driven it out on the road alone so I don't know about highway mileage.
  • pete59pete59 Posts: 6
    Is your 2500 a 4x4 or two wheel drive and do you have the Allison tranny?
    I'm looking at a two wheel drive with the Duramax & Allison six speed.
  • mattgg1mattgg1 Posts: 191
    pete59 -

    I have to ask...

    Why in the hell would purchase a 2500HD Duramax to use as a 100 mile/day commuter vehicle? Have you lost your mind?

    Why wouldn't you buy an inexpensive, new or used car that gets 35-40 MPG on the highway to commute in?
  • pete59pete59 Posts: 6
    That is a very valid question. No I have not lost my mind.... I am 48 years old and the knees aren't what they used to be. I have also had shoulder surgery so it's hard to get in and out of those small good gas mileage vehicles. I should mention that I am 6'5" 250 and that even makes it a little more rough. Besides I like to be able to sit up higher to see what is going on around me.
    Today I drive a 97 F150 and depending on the wind, get anywhere from 19 to 21 MPG. I do plan on driving the wheels off of it but want to be prepared for the after FORD years.
  • sullyaksullyak Posts: 30
    I have the 2500 HD crew cab 4X4 with the allison tranny. I haven't used it in 4X4 mode yet. And as I noted in my previous post with 2,000 miles on it I am averaging 16mpg with mainly highway driving. If I slow down to 55-65 mph I average 21-23(per the trip computer).
  • kacansas06kacansas06 Posts: 33
    I own the '06 4X4 now with 16k miles and Better tires than stock. I have gotten 27.5 highway once. I have gotten better than 25 highway many times BUT I drive it in it's best economy range which is in 6th gear with torque converter lock so that I can keep the rpm's to the 1200 to 1500 range. If you get it turning more than 1600 it WILL use more fuel. This means a lot of less than 60 mph driving, usually 58 or 59 is about 1400 rpm. It gets the best mileage at 52 to 56 mph and I am convinced some of the reason is wind resistance. A 2 wheel drive should do a little better if you drive it for economy. Remember that this truck's computers in the engine and the transmission LEARN how you drive and whether you want Power or you want gentle cruise for best mileage. This is the second vehicle I have owned that has these type computers and how you drive it makes a LOT of difference in mileage. The previous car was identical to the one my wife still drives which she can't get over 28 to 29 mpg out of and usually gets around 26, with a 4 cylinder. She is always tromping on it and then letting off when she thinks she's speeding then doing it again. Do that with the Duramax and you will get bad mileage.
    ALSO DO NOT trust the damn computer! Use a calculator and figure it yourself and it will always be better than what their display says. The engineers planned that display to have an actual fuel flow meter to gauge gallons used but it is NOT in the trucks as yet so they go by the fuel tank float position. NOT at all accurate. Mine usually says I am getting 16 mpg or so and the ONLY time it was close was towing 12,000 lbs of camper in the mountains at 80 mph(don't ask, involves wife and mother-in-law) when it said 8.1 mpg and I got 8.5 mpg.
    My other pet peeve is the damn automatic climate control! WHY did they put so far down on the dash and WHY not put controls for it on the wheel too? I think they want to sell front bumpers to you each time you hit the guy in front of you while trying to figure out how to control the cool air flow. No i have not done that YET but it feels all wrong. Other than that I love my Duramax, especially when people with their V-6 cars and trucks are getting worse mileage and spending more to maintain their vehicles.
  • kacansas06kacansas06 Posts: 33
    I want to get some decals or window dressing that tells the world my truck is a DuraMax and I Love my truck but so far I can't find any! Any body got any web sites or web stores or other reccomendations??
  • coontie57coontie57 Posts: 128
    That's some really good information you posted. Thanks.

    How do you lock in the torque converter? Are you referring to putting the transmission into the tow-haul mode?

    Another pet peeve of mine that you missed is the little button to put the vehicle into 4 x 4... way too close to the light controls and way too easy to engage without knowing. There should be a light on the dash that comes on or something. I am going to hate to ruin the 4 x 4 by running on dry pavement and not knowing its engaged.

    I knew the best mpg was down around 55. Pulling my 12,000 camper in Florida for 115 miles over to the interstate back in March I got 12.5 mpg or so (indicated via computer) and watching it drop when I hit the Interstate around Jacksonville to 10.5 at 70 mph.
  • agdocagdoc Posts: 3
    OK guys, I have had two F250 Superdutys, the first 1985 with 6.9, had to replace multiple injection pumps with the first one blowing a seal and filling my crankcase with diesel while in the Philippines, and the most recent a 2003 6.0L which i have replaced multiple EGR valves and most recently now in the shop looking at a $4000 repair due to blown head gaskets due to a failed EGR valve and EGR cooler. This after about 150K miles with all the routine scheduled maintenance and oil changes. (Called Ford customer care for some help --- the truck is out of warranty -- and was told there was nothing they would do, even though I have bought 5 new Ford vehicles over the last 20 years and have been very loyal. That's gratitude for you. Needless to say, I won't be back and told them so.

    So on to the Duramax. I won't be towing alot, but need the 4X4 and travel alot, so want a larger more secure vehicle, hence my desire for the 2500. I have been reading many of the posts and have seen the recs for keeping it under 65 and K&N air filters plus synthetic oils for better mileage. My concern is the Allison tranny -- great reputation but has anyone had any problems. Also anyone out there with more than 100,000 miles having any major problems or repairs.

    Thanks in advance,

  • kacansas06kacansas06 Posts: 33
    Last August I pulled 12,000lb camper and had the same thing happen. We did the first couple of hundred miles of the trip on 55 mph roads so I was running 50 to 55 then got on I-90 close to the S.D. border with MN and filled up in Souix Falls. That tank was 15 mpg the best of the trip. I NEVER got that kind of mileage out of my Suburban with it's gas 6.6L engine. The best I ever got towing with it was 12.5. City with the old Suburban was usually under 10 and sometimes as low as 5-6. When you are putting close to 40 gallons in that hurts. My average for the whole trip of 3500 miles was around 11.5 because most of it was interstate. The worst was in the mountains.
    Torque converter lock up occurs automatically when the vehicle reaches 45 or better and is in either 5th or 6th. It does it when the acceleration mode levels out and the load on the transmission and torque converter goes down. Putting it in Tow/Hual mode prevents lock-up. Also putting it in the M position prevents lock-up. The assumption behind this is that you require more power from the transmission. Did you know that the amount of power that goes to the rear wheels goes up in Tow/Haul because the torque converter oges into a higher fluid pressure mode? On the other hand you CAN tow a trailer in regular Drive setting IF you are not climbing or decending a lot of hills and do not have a load that equals over 75% of the Gross Carriage Weight Rating of the truck. For our 2500HD's that is a total load of 16,700 lbs so to be in Drive you must be under 12,500lbs for your TOTAL load. That includes fuel and people and anything in the bed plus the trailer. I carry extra fuel so I can take advantage of the best fuel prices while traveling. I use everywhere I travel with the truck and get the best priced diesel. When we retire and start traveling in it more I plan to sign up with a couple of truck stops for their fuel discount cards.
  • kacansas06kacansas06 Posts: 33
    To reassure you about the Allison 1000A which is in all the 2500 and 3500HD GM's you have to understand that it is the same tranny that they put in the GM 4500 with a 200,000 mile warranty. You can also buy an extended coverage warranty for the Allison when getting the truck from GM for 200,000 for less than $1,000. If you can't tell I have really done my homework on American diesel trucks before buying the Chev. I first wanted a Dodge but they DO have tranny problems with their automatic. Their 6 speed manual is Great but my wife says AUTOMATIC plus it is better for launching boats anyway. Then I desired the Ford because of the ride and the 7.3L engine. Then that went bye bye and out came the 6.0L to try to get mileage up for Ford. That has been a disater for them of nearly a billion dollars according to the Detroit newspaper and other reports I have read in magazines. So we finally drove a used Chev. 3500 dually and WOW what a nice ride and OGGles of power. Next came a new 2500 and a new 3500 and we were sold. But my wife insited on the SRW and like the ride in the 2500 just a little better(I could tell no difference) so that is what we bought.
    IF you are not going to tow, then ORDER your truck and tell them to override the standard 3.73 axle ratio and get the 3.42 and if possible get the 3500HD SRW which comes stock with 265 tires. WHATever you do ALWAYS check with your serviceing dealer about any tire size changes or addon computer controllers such as the Superchips because GM usually looks for ANY excuse to not payup on a warranty claim. Most dealers will allow you to use larger diameter tires and a computer controller if you let them know all about it so then you are covered because they enter the approval into the truck's VIN records with GM. At that point there will be no problems with warranty issues.
    DO NOT consider a propane injection, NitrusOxide, hydrogen injection, exhaust changes or any other physical changes to the truck until after the 100,000 miles for that WILL void the warranty. It says so in BOLD print in the owners manual so they can say you were warned. Good Luck!
  • dtimm6dtimm6 Posts: 1
    I have a used 2003 gmc 3500 with a flat bed body on it. 80k on the truck the truck came with a superchips in it and 4 inch exhaust no mufler. the biggest problem I have found with checking fuel milage is the amount of foam in the fuel as i am filling up. it has 2 tanks under the bed and fills the front tank and spills over into the rear. it takes a long time to fill the truck up. I recently installed a new fuel filter and Amsoil oil and on the next trip 2500 miles pulling a single car trailer 18.5 mpg running 75 80 i was getting 10 12 before.
  • agdocagdoc Posts: 3
    Thanks for the info. You have done your research and I appreciate your help.

    Getting close to the model end of year and have only been able to find a couple of trucks. Found a tricked out one that I like but they want 48,500 for it OTD --- literally has everything in it but is a 2500 SRW, not a 3500 SRW.
  • saulstersaulster Los Angeles AreaPosts: 48
    I bought a new 2007 2500 with the LMM diesel about a month ago, already 5,800+ miles. A few thoughts:

    The motor / Allison trans combo works great right out of the box. Loads of power, smooth. And it should get even better up to about 10K miles as "break in" continues.

    I was averaging about 17 MPG at an indicated 77 MPH on the interstates ( 70 mph speed limit areas ). After adding a tonneau cover, up to about 18 mpg. This is from refueling records, not the trip computer, which is about 5% off of actual per my tracking. And, per my dealer, that's pretty good for the trip computer, they see worse at around 10% off regularly. The trip computer runs off the fuel levels in the tank ( sending unit ), not actual useage by the motor. So that's a useful guide for comparison, not a completely accurate record.

    I also had a Transfer Flow 50 gallon auxilliary tank installed in the bed, giving me 76 gallons total on board. It's nice to have REAL range and buy fuel where and when I see the best prices. Very nice equipment and a great install at TF's headquarters in Chico, CA.

    I really like the additional information the trip computer provides, like the transmission temperature, the tire pressure monitoring system, remaining oil life, remaining fuel filter life, etc.

    I have yet to notice the burning cycle clearing the exhaust "soot box". I guess if I am not noticing, that's a good thing, it's not obvious or intrusive to the driving experience.

    For those in the Northern California area, I can highly recommend Dennis at GMC Vacaville ( CA ) for sales, a very professional gentleman to deal with. To date, the service department at GMC Vacaville has also exceeded my expectations. See Scott or Carlos there. Very easy to deal with, timely service, and very good attitude towards dealing with a few initial warranty items.

    I only have a few gripes:

    1) The gauges ( speedo, tach, etc. ) are very hard to read during the day. The white lettering and gauge indicators simply wash out in any kind of light, especially while wearing ( needed ) sunglasses of any kind ( polorized lenses or not ). This appears to be a "live with it" kind of thing and, yes, I did notice it before buying and bought anyway. ( Note - Great gauges and appearance at night! ) Anyone know of a vendor ( aftermarket ) with a fix for this?

    2) GMC did not provide an entry assist handle for the driver although all three other doors ( crew cab ) get one. I can't see any reason for this ommission, there is nothing on that windshield pillar to prevent putting a nice handle there except GMC failing to do so. I'll probably end up having some additional gauges installed there to get some benefit ( EGT? ).

    So far, so good.

  • glanoueglanoue Posts: 1
    My 2004 4X4 crew cab is a great truck the issue i am having is that when the truck sits for 2 or 3 days and I fire it up and put in reverse it will not move. I have to wait about 30 seconds and then lightly step on the gas petal to get it to back up. Has anyone else had a problem similar to this and if so whats the problem. Thanks
  • Hi Doc
    I own a 2006 crew cab chevy 4x4 duramax with the allison but currently only have around 35,000 miles on it. I love the truck and the only problem I have experienced was the power steering pump, which was replaced under warranty.
    But I do deal with a few Hot shot drivers that have 300,000 miles plus and they love the truck and have not had any problems, Talking to these people was the reason I decided to get one for myself. I totally decided against the Ford for the reasons you mentioned because several people I know had the same issues.
    Hope this helps :)
  • Check out or for the best looking decals on the market exclusivly for the Duramax.
  • Thank You to the people from harrelldesigns for the suggestion. Only further question I have is HOW these windsheild decals attach, inside or outside and just how weather resistant and also cold and road salt resistant these decals, all of them, including the ones on the body paint, will be given I live in the Twin Cities in MN. Yeah in the cold dark northland where they use lots of salt and sand on the roads in winter. Yes, probably a factor in the bridge collapse. Just look at the "southern bank" bridge supports in one of the many media pictures and you will notice that the "western" most concrete bridge support looks as though it broke off about half way down the pillar. Certainly that portion of the bridge is the ONLY part that fell way out of alignment with it's normal standing position. It fell to the east. Again thanks for the info. Plus i like the "Duramax SS" decals. Truck sure drives like an SS!!!
  • kbiggnkbiggn Posts: 2
    i need to change my fuel filter on my 07 . it has 15000 mil. on it is that normal and dose anyone know how to remove the canister housing to get to the filter :confuse:
  • kbiggnkbiggn Posts: 2
    hay max , i have an 07 crew short box. and i am not getting any better millage than you i have 15000 on my truck and it had 25mil on it when i bought it. i have talked to some other duramax owners at the fuel pump and some say they are getting 20 plus after break in. i hope it changes soon , like you i drive 35 mils to work one way . and was thinking diesel was the way to go. then the oil co. raise the price per gal. on fuel . also at 15000 thou. my info center is telling me to replace the fuel filter . hell the filter alone is 35 bucks.
  • The owners manual gives a LOT of advice about buying fuel for your diesel. I recently filled up at a station that had a not so clean pump and nozzle and my fuel filter life percent has been dropping ever since at a faster rate than I have seen in the past. I also have seen advice about additives to the Ultra Low Sulfur fuel for lubrication of the whole fuel system. ULS diesel seems to run fine without any additve but the simple one of using a small amount of my unused but fresh clean engine oil seems to be the best. I have been doing that for the last year and have seen no ill effects on the engine or fuel system.
  • I have just got a 2007 chevy 2500 classic 4wd cc
    dealer filled it up, I did not reset fuel econ and it was 13.3 mpg / I drove total 475 miles @ 55/65/70 mph the DIC said I used 27.1 gallons and 17.9 mpg.
    When i filled up I put 24.1 gallons in tank to fill it up.
    Where did the other 3 gallons go???? you can't always believe the DIC. 19.7 mpg's first tank of fuel.
    Changed to oil to Delo 15-40 LE.
    I would like to change air, exhaust, whatever to get more MPG's if I find someone who has done it successfully.
  • I now have (11/07) about 16,500 miles on it and on our recent trip to Myrtle Bch I was getting about 12.7mpg on the flat land pulling the 12K camper. I thought that was good. I still have not driven it without a trailer of some kind. Around town its about 16mpg.
  • I have 8500 miles on my 2007 2500 4X4 and getting a consistant 15 mpg by the computer. This doesn't seem to vary towing my Airstream trailer or not. Since I'm new to the Duramax, is this mileage typical or should I be getting better? I hear others getting 19 mpg with the same truck. I try to keep my highway speed around 65-70 mph. If not typical then how do I get better mileage?
  • I have about 2200 miles on my new 07 2500HD 4x4, and only averaging around 13 MPG so far. Those are combined in town and highway miles driven at 65 to 75 MPH, and some small trailer towing. It's still increasing at each fuel-up, so I'm hoping it will reach a 17-20 MPG range when it's fully broken in.
  • After seeing your 13 mpg, I don't feel that bad! I also have a Trac-rack ladder rack with extension on my truck and wonder how much that effects mileage. Also how much of an improvement should I see after break in. By the way, how many miles should the break in period be? Good luck with yours....
  • About 100k on a 01 2500HD that I love. Would not start this morning at all.
    Yesterday morning it started and stalled and re-started fine. No other noticable indications prior to this event. Saturday after Thanksgiving, raining in Houston unable to get anybody to have a look until Monday. Any suggestions?
  • I just traded off my 99 2500 gaser for a used 05 2500HD with the Duramax. Can anyone provide some information to this diesel ignorant guy. Everyone says they love their Duramax, but I have a lot to learn. Definite dos and don'ts, things to watch for, fuels and additives, oils, etc. I also hear a lot about chip installation to improve performance and mileage but don't know what to believe. Any recommendations or advice would be greatly appreciated!

    Thanks to all,
    (for the 48 chev I'm rebuilding in my spare time)
  • Hello all....i am new to here but not new to diesel trucks....I have an 06 2500 dsl and think that i am having injector problems but not sure. the fuel mileage has dropped by about 4 mpg and the truck has 32500 miles on it. I was wondering how they figured out to replace your injectors? any info would be appreciated.
  • I have a 2003 Silveraldo Duramax and have recently experienced the not starting and it wasn't the battery or glow plugs. The not starting (it would crank but not turn over). Ended up having the Glow Plug module replaced.
  • rseeborseebo Posts: 12
    I too have an 05 Duramax, but not feeling the love for it. I have heard from other owners and mechanics that the 05 LLY motor is one of the worst that GM has come out with. I have had several problems, Turbo went out, rear seals went out and constant over heating when towing my toy hauler. Same issue, overheating, that all other people I speak to have and am now experiencing my speedometer not working. I have the Banks 6 gun w/speed loader and it and it runs well, just overheats. If you have allot of miles on it, I would suggest running whatever oil they have run. I wouldn't change to a synthetic. I get about 17 - 19 MPG on the HWY at 70 MPH not towing w/285 tires and 10 - 11 towing 10k toyhauler at 60 - 65 MPH.
  • First point to make is that if you look at the LACK of aerodynamics on the front of the truck and the fact that a LOT of air gets to flow under it then you have your answer to lower fuel mileage at 70mph or faster. In my Duramax I can hear the engine start to work harder as I pass through 57-58mph and a significant increase from 65-66 to 70. SO I cruise Interstate at 60-65, usually with cruise at 63-64 and get 22-24mpg depending on conditions. If I slow down on a state highway to 57-58 it goes up to over 25mpg. I DO NOT trust that dam computer and always calculate my own mileage which shows the computer to be off by as much as 5 mpg for city driving and 2-3mpg highway.
    Last point to make is that you have the wrong tires for the transmission programming. If you bought it this way you may need to find out if the computers were recalibrated for a larger tire BUT the largest GM calibrates for on a 3/4 ton is 265 and on a 1 ton 285. The computers CAN be set for your tire size on a 3/4 ton but you will have to find s dealer or other shop that will exceed GM reccomendations. Your problems are the biggest reasons GM did not recomend 285's or larger. I towed 12k travel trailer last year and averaged 12.5mpg on the whole 4000 mile trip but some of it was in mountains where it dropped to 8mpg. In the flatlands at interstate speeds I got 12 to 15 mpg depending on speed. Off the interstates I got 15 to 17 running 50 to 55mph. Pushing the brick that is our truck through the air gets harder over 50 mph.
  • nlccnlcc Posts: 1
    i just bought a 2002 2500HD ext cab 4X4 (227Km)with a Duramax and Allision tranny. Best mileage so far is13 Cdn gal highway empty at 60 mph 280 mile trip...worst was 6 kicking around the ranch and to town empty. New fuel and air filters..Truck is going back to the dealer tommorrow to try and find out whats wrong.
  • I have an 01 2500 HD. First, a fuel additive is very desirable. I haven't been able to tell any difference with the additives found at the grocery store. The better ones come in two types. If you live in a humid environment, one type has additional antifungal treatment. If not, the other type increases cetane (same as gasser octane), injector cleaners, and lubricants. I have not upgraded mine as of yet except replacing the stock filter with a K&N, nice difference. Synthetic oil is a huge overall recommendation. I have studied various chips and it seems that Edge and Banks seem to have the features I would like. I have also read many posts about MPG and determined that the old LBY does a little better. Highway, almost 23 mpg @ 75-85 mph, 11mpg towing a high profile 13.5klbs. I found the gas pedal is really sensitive and using the cruise control or jamming my foot against the X-mission tunnel seems to reduce pedal variance and increase mileage. Intake, exhaust, chip, electric fan are my next upgrades, $$$$.

    Happy Motoring,
  • lnilni Posts: 1
    I have a new 2007 duramax. The indicator lights in the day light mode are so dim, I can't see them. They are fine when its dark.
    I think this is a programmable problem. Have not had the first service yet. Milage is 15.2 average so far. Very pleased with the towing. 7500 lb 5th wheel. Need larger wheels and tires. Any ideas would be appreciated.
  • Hi I am in the market for a new diesel truck and not sure what to get I have had many diiesels in past and have now a 2007 dodge mega cab with 6.7 diesel auto .But always broke down and gets terible mileage. 11 on hwy and 9 in town and 3.9 pulling a 7000 pound trailer. so any feed back would be great also I do have 35 " tires but I drive like an old women to try and improve mileage dont work. please help [email protected]
  • I have a 2006 3500 crew cab long bed 4x4 with a six inch Fabtech lift and 35/12.50 17 pro-comp x-treme a/t tires. The motor is all stock and i get about 11-12 mpg around town and 10-11 mpg towing a 7000 lb. travel trailer. Never owned a diesel before is this normal gas mileage? Very happy with everything about the truck, even the gas mileage if this is all i can get, because it is a very large truck.
  • nedzelnedzel Posts: 787
    Mythbusters recently did a segment on acetone. They found that it slightly reduced mileage. YMMV.
  • I have a 2004 Silverado 2500 Crew Cab with the duramax. I was running on the interstate at 80 and I was only getting around 14. Is this right? What is the injector problems all about? Truck does not seem to have full power when you punch it, it has better power at 3/4 throttle. Could one of my injectors be faulty and is making me get horrible mpg and power loss? Thanks!
  • Mythbuster didn't used the recommended ratio though. Acetone is still very much speculative but it is interesting that some folks swear by its efficacy.
  • We just purchased a 2005 Chevy Silverado 2500hd diesel. It has the radio controls in the steering wheel. They work fine, but we cannot use the radio on the dash board. We can't change the time, can't use the volume button on the dash, can't program our radio stations. Not sure if we need to tear apart the dash board or what. Any suggestions before we go and do that?
  • KCRamKCRam Mt. Arlington NJPosts: 3,516
    Welcome aboard!

    Since this is not a diesel issue, you'll get a better response asking your question over in the Chevy Silverado and GMC Sierra Audio/Radio discussion.

    kcram - Pickups Host
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