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Chevy Silverado and GMC Sierra Duramax Fuel Mileage



  • I am getting a set of 285/75/16's put on this Friday. What do I need to do to dial up the Torsion bar? Also I am told I will need to get the dealer to calibrate the speedo. Is this correct?

    I would love any help I can get here. I just don't like the look of the 245's. Also was always getting stuck in the back yard if it rained. Figured that the wider tire may make the truck "float" a little better in the mud.

    Any help is appreciated.

  • victorycruiser

    When I put on the 285's I found my speedo was off about 5 mph. I went to the dealer to recalibrate my speedometer and the dealership told me that Chevy will not recalibrate the speedo on duramax trucks. Stupid huh? But I seen a recalibration chip by superlift for about $190. In case your tire shop doesn't tell you you need to get an alignment after raising the torsion bars.
  • The 285s will definitly fill the wheel wells better and make the truck look better. Everytime I've put 285s on one of my duramaxes, the right front will rub. If ya put splash gaurds on it's worse. By raising the front end with torsion bars is easy to do by reputable alighnment shop and a slight alighnment is needed. It will also rais the front end, leveling the truck.
    As for the speedometer: A difference of 2-3 mph faster than it shows. Not a big deal for me and I've never worried about it or inquired about an adjustment.
  • Is the LLY the new Duramax that is coming out with the 06 trucks? I am thinking of waiting for the new engine but it is not widely available.
  • Is anyone driving the NEW 2006 Duramax diesel yet? I'm thinking of ordering one with the new engine and am curious regarding fuel mileage in the 2500 truck.
  • KCRamKCRam Mt. Arlington NJPosts: 3,516
    According to GM's press release, the new higher-output (360/650) Dmax won't be available before November.

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  • My son works for the other guy (Ford) as a mechanic on their diesel engines. They have had a lot of trouble with their variable turbos, and guess what, GM is going to use the exact same turbo (from the same manufacture) in 06' from what I have been told. Anyone else heard about this?
  • Not true. After installing BF Goodrich ko's 285.75.16, I took my '05 2500HD to the dealership who reclaibrated my speedo (at no charge). Before I put the tires on, I had a leveling kit put on (changed out the torsion bar keys). This lifted the front 2.5 inches to be the same height as the back ($275 installed). Friday I had the front shocks replaced with Blistien 5100 shocks ($250 installed). After doing the leveling kit, the shocks were extended to far, and gave a rougher ride. The new shocks make a washed out dirt road feel like a highway! Didn't turn the torsion bars at all. I did have to trim a little of the front valence to keep from rubbing though. Go with the BF' wont get stuck.
  • Under the current GM pricing I could not find anyone that would sell a DMAX with the LBZ engine. I couldn't give up the 9 or 10k off MSRP for an engine upgrade. Has anyone had experience with the 6 speed Allision Auto?
  • i have read that replacing with the stock shocks with the blistien shocks is suppose to make it better. i personally have not done it. as far as fuel economy goes,it did'nt seem to make any difference before or after the lift . i have 265/75/16 tires.i get just about the exact same milage you are stating. i don't know how they are getting the milage they say they are. i've tried driving a constant 60 m.p.h and i might get an extra .5-1.0 mpg more. .one thing that i did try and is pretty inexpensive and seems to work the best is using acetone in my fuel. approx 2 ozs per 10 gallons of fuel. it seemed to bring it up around 2 m.p.g. go to yahoo search and type in acetone diesel. click the first item. big article on using acetone. try it and let me know what you think? Aarongd
  • Benr,
    Yes, I have the 5 spd. Allison Auto Trans, and I always use the tow button. I will have to try it without the tow button on to see what MPG I get. I guess I was just afraid of burning up the tranny if I didn't use it. I use cruise control alot and try not to stomp the gas pedal, I try to keep that to my race car. :)
  • The new DMAX with the LBZ engine will start hitting the production lines next week and should start hitting the streets soon after. I just bought a 2006 with the LLY motor that has a lot of the upgrades of the new LBZ motor and it made a huge difference over my 2004. The mileage appears to have increased 3-4 mpg with the modified LLY. With the increased fuel pressures of the LBZ, this may not happen since usually more HP/Torque usually means more fuel (but who knows). Chevy wouldn't even tell me what to expect with the modified LLY.
    The 6 speed seems great, shifts smoother than my 2004 did and definitely likes to go fast. I would suggest buying now and saving $10,000 and see what happens with the newer engine. Also, I hear that Bully Dog is already designing new performance parts and looking for testing people on their website.
  • I have a 2002 2500 HD ext. cab and was wondering what common fuel mileage is? I have had an all time best at 25.4.miles to the gallon on the highway. I love the quietness of the Duramax too. Towing I have had an all time best of 17 MPG with a 6,000 pound enclosed snowmobile trailer. Just wondering how many more trucks are like this?
  • stonegstoneg Posts: 47
    As for the ride...night and day. However, my mpg are at 10.5 today...I'll be hunting up some acetone tomorrow. About 5 ounces for a 26 gallon tank?
    I just ordered the Edge Juice with Attitude (will be using level 1 for better mpg's, but level 3 or 4 to embarrass these kids with "tuners?" from time to time) and it will be here in about 2 weeks, and will report on its efects.
  • stonegstoneg Posts: 47
    WOW, you must only drive WITH the wind. I couldn't get 25 mpg if I was chained to the back of an 18 wheeler!!! Some of us are getting 10 city, and 14-15 Hwy. Damn your lucky.
  • stonegstoneg Posts: 47
    Has anyone found a way, other than the piller, to mount the Edge Attitude Monitor on a 2005 GMC? My friend has an 02 and found a billit console cover mount for it on Ebay, but the overhead console in his truck had a larger opening in it than mine. I saw another overhead mount on Ebay for about $45 + $15 shipping, that says it fits all makes, but want to know if anyone has tried it or other products.
    I dont like the piller mount, and prefer not to drill holes on the dash to mount it.
  • I have a question for all ya's, I own a '05 silverado with a duramax. The problem that I am experiencing is that from time to time especially when I am in the throttle passing someone the engine would die down and won't go over 2000 rpm. I acts like when the fuel would start to gel in the winter. Then I would have to get totally out of the throttle and wait a couple of seconds and then usually it would go back to normal but not all the time. I put a scanner on it and the are no DTC's in the ecm. Did anyone have this problem before? I am thinking that it might be emission related but not sure. If anyone has any input please let me know. THANKS!!
  • Your lucky!!! my '05 is lucky to see 15.6 highway and I rarely get in the throttle.
  • stonegstoneg Posts: 47
    I purchased the black molded plastic mount that says it fits all GMC's, Chevy's, Fords, and Dodges. It doesnt fit, althought it may be due to the sunroof option.
  • stonegstoneg Posts: 47
    Is there a difference in the overhead console on the 2005 2500HD with the sunroof option and ones without??? Aren't they the same size?
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