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Chevy Silverado and GMC Sierra Duramax Fuel Mileage

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  • I just bought a new 2006 2500HD 4x4 crewcab Duramax with 106 miles on it. I am going to run B20 BioDiesel in it no number2 diesel. I will post here to let you Duramax dudes know how things are going.

    All my research tell me this fuel with its extra lubricity will help diesel engines run smoother burn cleaner and free up any build up from using #2 for long periods of time. If you have been using #2 and switch to B20 you will have to change you fuel filters every other tank of fuel for about ten tanks because the biodiesel acts as a solvent and loosens the accumliated deposits in the fuel system and tank built up from the #2 diesel.

    Here goes just bought my first tanks today and KNOX super stop in Dallas Texas. ;)
  • KCRamKCRam Mt. Arlington NJPosts: 3,516
    "Water remover" usually doesn't do the job. If the fuel system detects water, you've got to drain it. Diesel is lighter than water, so the diesel will sit on top of the water in your fuel tank - pouring additive will thus not get to the water. But since the pump draws from the bottom of the tank, the water will get pulled to the engine first.

    You also need to find the source of the water - either a leak, driving through a deep puddle, or bad fuel.

    kcram - Pickups Host
  • You mention running #2 fuel instead of #1.
    Is #2 the off road dyed diesel?
    I'm hesitant to void my warranty.
  • gagricegagrice San DiegoPosts: 29,173
    Number one diesel is really kerosene. It will not gel at low temps. It is also used in jet aircraft. Commonly referred to as JetA fuel. It does not have the lubricating characteristics of number 2 diesel. We only used number 1 in our trucks in the Arctic, year round. I would say you are better off with number 2 diesel unless you have sustained temperatures of minus 20 degrees F for extended periods of time. Biodiesel gels at a higher temp than number 2 diesel. Most gas station in cold areas add a bit of number 1 in the winter to protect against gelling.

    PS
    most dyed diesel is number 2 used for tractors and off road use only. Big fines if you are caught with it in your on road vehicle.
  • Has anybody upgraded their exhaust? What did you buy, and how has it performed??
  • mek0123mek0123 Posts: 33
    My brother has a 2004 Silverado LT 3500 with the Duramax Diesel that he ordered new with every available option and when he test drove two other Chevy 3500 model trucks prior to ordering his, the mirror control button would allow him to electronically fold in the trailer tow mirrors. He just recently realized after two years of ownership that his truck will not do this. GM nor the dealer has been of any assistance at all, after three calls/visits to each. Any idea why his won't work in this manner? Thanks and we both would appreciate any assistance at all.
  • I just bought a 06 2500HD crew cab with the duramax/alison combo. I about spent all my retirement buying this truck and thought it would be a great replacement for my 1/2 ton and 1 ton. I love the truck but it gets the worst mileage out of all three! The first few tanks got 8-10 mpg and after a highway trip(unloaded) I still only get 13.8!!! Is there something wrong with this truck? If not, I think I wasted alot of money. Is there something I should make the dealer look at. Surely it must get better mpg than that.
  • I have about 10K miles on my 2006. I am averaging around 13.8 also. SUCKS. Something has to be wrong, however Chevy simply says if it does not have an engine code, they have no where to go. Brain dead mechanics. My 2004 Duramax averaged 17 to 18 in the city and got 22 when I drove at 2000 RPM. My 2006 mileage drops when I drive 2000 RPM. Let me know if you find anything out.
  • I just got off the phone with the dealer. They said they are researching what the mileage should be?? I could save them time. Do they think I didn't research all this info before I plopped down the 50K for the truck? My buddy's '04 gets 23mpg unloaded and 17-19 fully loaded. I have noticed that it is getting better with more and more tanks ran through it. I am praying that as it breaks in it will get better. I will keep you posted. After paying that much for a new truck, I will bug the dealer everyday until they give me another one if it doesn't improve.
  • coontie57coontie57 Posts: 128
    I bought the same truck in July... I get 11 mpg pulling my 11000 camper in the mtns... and I got 18.8 over 250 miles driving in the mountains of VA and NC back when it only had 500 miles on it. still only has 3500 on it

    Are you sure you don't have the NON MPG rear end..??

    Incidentally I pulled up Saluda Mtn I 26 today at 60mph.. shifted manually to 4th and had plenty of power left to accelerate if needed... My 250 Ford back in May could only do 31 - 32 mph... in 2nd and the engine at 2500 rpms or so.
  • I think you need to drive it some as I had a 2003 that got 21 mpg and now drive a 2004 that gets 20-21 (thats US gallon too). They have great power and this mileage is my combined city and highway as it improves on long trip by 4mpg. Lots of idling and or city driving will obviously not do great for mileage but these trucks do well on fuel in my experience.
  • I bought a 2006 Sierra 2500HD Duramax w/6 speed Allison Tranny and took two trips from MI to TN since May and was getting around 19MPG. Had the fuel filter and EGR valve replaced, then took another trip to TN and now am getting around 17MPG. Went to the dealer, they found nothing wrong. Suggested it could be the cooling of the air temperatutre making the mileage change????
    Also, is the new ulta low sulfur fuel going to make my injectors go bad? If so is there some additive I can put in?
    I am a first time Diesel owner and I read the label on the truck and it said to use Low Sulfur Diesel and the fuel pump that is Ultra Low Sulfur Diesel says "Approved for all diesel vehicles". Am I using the right stuff?
    Thanks for any help.
  • I have been waiting to take a long trip with no load to make this post so here tis. This week I had to drive to the other end of NC... a trip of 320 miles each way. On Monday the weather was in the 60's and I ran about 60-65mph and the numbers from the computer said consistently on flat land that I was getting 20.2mpg with 5000 miles on the truck. Yesterday it was much colder... 32 -- 39F and I was in a bigger hurry... 70-75 mph... mileage dropped to 18.8 mpg..

    I guess it doesn't PAY to be in a hurry or drive in cold weather or both.

    Does anyone know if the colder weather has much impact on diesel fuel mileage?

    Does anyone know what parameters the computer is measuring...? I suspect that the numbers are representative of the average of the last 100 miles or something.
  • In reply (Coontie57), from my coworkers that have diesel pickups, (Ram 2500/3500 models), if you keep your mph at 65-68, that is the sweet spot for fuel economy. When you get above 70mph, a 10%+ efficiency drop in economy is the norm. I've noticed the same about my 2001 Grand Caravan ES. 58mph is the sweet spot for economy. 24.5-24.7. Run at posted speeds of 65-70 and I get a 20% drop in economy too recording a 19.9-20.1 mpg average. Just an fyi!
  • I had a Ford 250 diesel before and got comparable mileage at 70 mpg... but the vehicle was well broken in then...

    Any thoughts on the cold weather affecting mileage.
  • KCRamKCRam Mt. Arlington NJPosts: 3,516
    My Ram diesels (had 96, now 05) drop about 15% in winter. That's more from using winterized diesel here in NJ than the cold air itself.
  • Thanks for the information. I thought so but just wanted to be sure.
  • nbowenbowe Posts: 1
    I just bought a 2004 duramax and threw an edge juice attitude in it with a high flow muffler.Running 75 down the high way in Montana, I got 17.1 mpg.My computer showed 21.9.Any ideas why the computer is so far off ????Should I put a higher rear end in it? What does any body know about intakes?Just curious
  • do you know what the baldwin fuel filter # is for the 06 durmax. my parts house doesn't know it yet.
    from Riceguy
  • coontie57coontie57 Posts: 128
    Right after the first of the year I took this trip again down I 40 heading East out of Asheville. its about 350 miles each way and again without too much in the truck and not pulling anything. I got 20.2 mpg on the way from the mountains to Greenville, NC.. I checked it in the areas where its fairly flat. the temps near 70 F. Speed 65 - 70mph

    On the way back the temps were 72 last Sunday and not cold a bit.. again I got nearly the same mileage 18.6 this time but had a stiff wind that I was driving into. Cold weather was not a factor this time it simply has to be the slow uphill trip from Greenville, NC elevation of 50ft or so to Marion where the mtns start which is 1000 ft or so... its 2400 ft where I live.

    That 300 mile stretch doesn't appear to be uphill but I guess that's doing it. 65-70 miles per hr. I have 7100 miles on the truck now and have changed the oil once but not the fuel or air filters. We are leaving today for FL pulling the camper at 11500 lbs.
  • I don't know for sure but I suspect that the Juice chip causes the rail pressure to increase which allows more fuel to push through the injector per time. the mileage computer is likely programed to calculate amount of fuel used based on the time the injector has been opened. With the increased pressure more fuel is going through the injector than what the computer "realizes"
  • i have 05 lly and a 06 lbz,the lly is a one ton dully stock i got 15.8 mpg,but with dual 4"exhaust and ppe programmer i'm now getting average of 22 mpg on the highway,and on the lbz,it is a 2500hd crewcab shortbed stock i got 18 mpg but putting single 5"exhaust and ppe programmer i now get 22 on average,the stock exhaust leaves alot of back pressure there for taking more power to run the truck
  • Sounds like there might be an issue with your truck.
    I have the same identical truck as you and mine has been averaging 20 mpg from 55 mph to 60mph about 19mpg at
    65 mph and about 17.5 mpg to 18 mpg @ 70 mph.
    I also tow a 35 foot 5th wheel that weighs 11,000 lbs and I get 11 mpg to 12 while pulling flat surface at 65 mph.
    I checked the mileage the old fashioned way to verrify the computer but the computer was actually pretty close. The only thing I have done to the truck is replaced the stock donaldson air filter with a K& N AND I run Amsoil 15w40 heavy duty synthetic oil
    I hope this helps.

    Mike
  • I JUST BOUGHT AN '07 SILVERADO CLASSIC 2500 HD CC WITH THE DURAMAX THIS PAST MONDAY, THE DEALERSHIP FILLED THE TANK FOR ME BUT ON THE DIC DISPLAY IT SAYS I AM GETTING ABOUT 12.5 AND I HAVE USED A QUATER TANK SO FAR. A BUDDY OF MINE HAS A WORK TRUCK REG. CAB WITH 2WD AND HE IS GETTING CRAZY FUEL MILEAGE. THIS IS MY FIRST DIESEL SO I AM NEW TO EVERYTHING BUT I THOUGHT THE TRUCK SHOULD GET A LOT BETTER FUEL MILEAGE THAN THAT. ANY SUGGESTIONS ?
  • I suggest you reset your computer info (fuel used and MPG) Fill it up again as you do this and see what it does. I always get better than that and I got my 06 in July.. 20.2mpg at 65mph... 14-15mpg around town.. I have 8500 mi on it now..
  • I HAVE NOT TRIED RESETTING THE FUEL USED AND MPG BECAUSE I HAVE NOT HAD TO FILL UP AGAIN, BUT WITH THE 2500HD 4X4 CC WHAT IS THE IDEAL FUEL MILEAGE WITH 3.73 GEAR RATIO CITY AND HWY NOT PULLING ANYTHING. ALSO DOES ANYONE KNOW IF THE K&N AIR FILTER HELP AT ALL, WHEN I HAD A 1500 I HAD THE FIPK KIT AND IT HELPED SOME, JUST WONDERING WITH THE DURAMAX.
  • I have a 2006 Silverado 2500 Crewcab with the duramax and 373 gear ratio and 6 speed alison transmission.
    my actual gear ratio has changed a little due to the fact I took the 245 tires off and went to a taller 285.
    My truck has 25,000 miles on it and just installed a K&N air filter, I can't see alot of difference in mileage yet but it does not blow black as much under a load pulling my 11,000 lb 5th wheel. After taking into consideration the speedodometer is off 6 mph at 70mph and I actually travel 1 and 2/10th's for every mile showing on the odometer, I get around 15.5 to 16 in town and 19+ if I keep it below 70mph.
    I also get about 12 mpg pulling a 11,000lb high profile 5th wheel on flat grade.
    Point of consideration, When I installed the K&N air filter my check engine light came on within 10 miles of travel.
    K&N recommended I disconnect the negative battery cables from both batterys and leave disconnected for 3 and 1/2 hours. After I did this I reconnected the batterys and the check engine light was still on, but after I shut the truck off and restarted it for the second time the light cleared and has not come back on,
    Hope this info helps you.
    Mike
  • I purchased a 2007 Chevrolet 2500 HD 4x4 in October 2006. I have now got about 12,000 miles on the truck. I have been getting about 17-18 mpg normal driving (highway not towing). I purchased this truck (first Chev) due to the reported great fuel mileage of 20-24 mpg. What can I do to improve my fuel mileage. I am already driving slow at or below 65mph. Can anyone out here help ?
  • You are getting about what I get on my 06 chevy with 8500 miles on it... 18.8-20.2 mpg on the hwy with no load and 65mph.. I hope it gets better with more miles. I don't expect the engine to be broken IN until 25000 or so... Its too early now to tell.
  • I am only getting about 17-18 mpg at 65mph. I have not topped the 18 mpg barrier.

    Thoughts ?
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