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Chevy Silverado and GMC Sierra Duramax Fuel Mileage



  • stonegstoneg Posts: 47
    I put about 5 oz. in my 26 gallon tank, and I picked up about 1 mpg, but I just installed the Edge Juice programmer, and put in on level 3...picked up 1.7 mpg, and 75 HP!!! I was getting over 2 mpg better, but when you have an extra 75 HP, its hard not to use it. I spoke to the owner of a Diesel specialty shop, and he has never heard of using the Acetone, but is now researching it. He is also skeptical of using biodiesel, saying that nobody knows the long term effect on the engine. Any comments on biodiesel? Also, I think I found out why my mpg suck so bad, 4.10 gears, instead of the 3.73
  • I am a diesel mechanic for about ten years and the fleet company that I work for uses veg. oil mixed fuel in some of thier trucks since they got them, and those trucks have over three hundred thousand miles on them and still run like a top. the mixed diesel is similiar to biodiesel cause both use veg. oil. I know some guys that use biodiesel and the see no difference. But, as for the acetone thing I wouldn't recommend using it cause it has a lower flash point than diesel does and it will actually cause the motor to pre ignite causing misfires. Its on the same basis as putting gas in your diesel. cause gas has a lower flashpoint than diesel and will do the same thing.
  • stonegstoneg Posts: 47
    Yeah, I am a little nervous about adding it again.
    This past fill up, I added an additive by Stanadyne that I got from Shivers Diesel, and along with the Edge Juice programmer on level 1, I went from around 10 mpg to now almost 14. The exhaust is on order, and hopefully I will get another 2 mpg increase if you believe all the hype.
  • I drove the Dmax roughly 500 miles the first day. Trying to get it back home. I averaged about 17mpg mostly highway doing 75mph. The next day having to drive the last 100miles I decided to keep it around 1600rpm. That put my speed at around 63 in 6th gear. Trying to keep it in peak torque range. Averaged 22mpg freeway only. It seems to average about 15 mpg mixed. The 6th gear really helps with increasing the mpg.
  • I am following this article for break in.

    And on DMAX the has alot of info.
  • stonegstoneg Posts: 47
    so does the 3.73!!! The 4.10 in the '05 sure isn't helping.
  • Just curious if your mileage is calculated manually by you when you fill the truck or if you are reading off of the DIC. I have found that the DIC mileage is way off. I have an 2004.5 LLY motor in my GMC Sierra Crew Cab Short box. My lifetime mpg average at 15,000, calculated by me from fuel reciepts is 17.8, this was a mixture of highway and city. I just finished putting a predator programmer (fuel economy mode selected), MAC intake, and a Jardine 4" exhaust. Today I took the family to Chicago and back running 75mph the whole time and average 20.1mpg based off of actual miles traveled divided by the actual fill...the DIC showed 26.5mpg??? I am very pleased with 20mpg. I believe I can get up to 21mpg if I hold it at 65mph, or essentially keep the motor below 2000rpm which is where everyone on the forums states they get the best mileage. Glad to hear you have the Allison with the 6 speed.


  • stonegstoneg Posts: 47
    Sorry fellas, I mentioned before that I took my 05 CC D-Max to my dealer to recalibrate the speedometer for the 285.75.16's, and now I am beginning to wonder if they did anything at all. I recently installed the Edge Juice with Attitude, calibrated it for the 285.75's and there is a noticable difference in the speed. I am now thinking that I am actually getting better MPG than shown or hand calculated, because the truck is actually going further with each revolution than the computer is calibrated for. I guess the only way to find out for sure is to get on the open highway, reset the tripometer and take a look upon passing 100 mile markers. I'll bet the computer says I have traveled less than 100. (sure hope those DOT boys are accurate!!)
  • I am considering buying a new 2006 DMAX, 2500HD 4x4. What kind of everyday mileage are you getting city/hwy and is your DMAX a 4x4? I plan to use the DMAX to pull a camper but the majority of the time will just be for driving back and forth from work. Thanks.
  • Is it the new 360 HP / 650 lb-ft DMAX? I am also thinking about getting a 2006 2005HD 4x4 with DMAX. I was just building one on and saw a 360 HP DMAX as an option for 2006. I ruined a pair of perfectly good pants! :surprise: Dang! I guess the Torque wars are far from over. Dodge and Ford better step up to the Chevy, or Chevy will just keep eating them for breakfast. :)

  • stonegstoneg Posts: 47
    update....yes there is. If you are looking at adding the Edge with Attitude monitor to your 2500HD, and it has a sunroof, the overhead console mount on Ebay will not work for your truck. Also the black plastic one that says it fits all makes and emodels will NOT work if you have the sunroof option. You have 3 mounting options: Use the supplies mount, use a pillar mount, or what I did, drill a small hole in the smaller of the two lower consoles for the wire to go though, and sqeeze in. Its rare that people in the truck ever even ask, "hey what's that?" It just doesn't look like it has been added aftermarket. If you DONT have a sunroof, the overhead console mount with the two built in auxillary switches looks awesome.
  • stoneg if you don't mind me asking where did you purchase your aftermarket torsion keys at ?thanks
  • funny you should ask. today i had the exact problem you are talking about today. i also have an 05 duramax. could"nt get the rpm's above 2000 rpm's. you described my problem to a tee. it's on the back of a flat bed as i speak. will let you know what the problem is after it get's back from the dealer!!
  • the dealer finally figured out the problem. it was a clogged fuel filter!!! i have 16,000 mi and i can't believe it was clogged!!! and they wanted to charge me $180.00 to fix it. say's it wasn't under warrenty!!! say it's like an oil change. good thing i spent $49,000 on a chevy. might want to get your own from a parts store!!!!!!!!!!!!!
  • stonegstoneg Posts: 47
    at a place in Tallahassee, FL called MINCO
    If your nowhere near here, look on EBay, I've seen them there for, I think around $40-$60. After you change them out, you'll need to get your truck re-aligned. If you want to get that "cadilac" ride back after the torsion key install, switch your front shocks out to the Bilstien 5100 series. These shocks are longer to accomodate the 2.5 inch increase in height. I didn't do it at first, and the ride was pretty bad going over even a speed bump at low speeds. It seemed as though the truck would "top out" causing the truck to slam up and down. If you do it (highly recommended) go ahead and spend the extra $100.00 on the shocks. I have seen the shocks in accessory catelogs for less, but I had minco order and install these as well. I get lots of compliments at stop lights, gas stations, etc. for the way the truck sits level. Good Luck.
  • I have an '05 2500HD Crew 4x4 D-Max/Allison... I love this truck. I bought her new on May 1, and since then have put 18,750 miles on her. This truck is my daily commuter, not to mention I've towed everything from bobcats with a total load of 12k on the ball hitch to little pup trailers. I have found my normal unloaded mileage with my commuting around the DC area, has averaged 17-18.5 mpg's, on the highway unloaded I have found I get about the same but I'm holding 75mph.
    I have a K&N filter in mine, and haven't noticed a difference in the mileage or performance at all. One thing I noticed that did cause a change in my MPG's was source of the diesel I was using. I have found that getting my diesel from a quality supplier helped in my MPG's.
    I'm currently looking to level my truck and put 285's on her. I'm planning on using a kit from ORU ( and they sell the kit with the longer Bilstein 5100's for a little over $400. I'm also looking at putting in either a Banks Big Hoss kit, or an Edge Juice with Attitude monitor, with the appropriate opening up of airflow. Any one have any suggestions or stories about using either of these 2 particular products?
  • I have an 01 X-Tended Cab 4x4 with the Allison and D-MAx of course. I live in Iowa where winters are kinda cold. This is my first Diesel and I'm curious to what anybody else is using for engine oils out there. I can't afford Amsoil or Royal Purple, but any info would help. By the way, I get 19 mpg city/ 24 highway. Thanks
  • I have a friend with a 2004 ford f-250 with the Edge Juice system, air intake system and aftermarket 4" exhaust. It tore his truck up. He had to put a new tranny in it and just before he got rid of it the motor was running really poor. Ford wouldn't replace the tranny under warranty. Not a cheap tranny for him. Personally I would go with the Banks system and upgrade the tranny with a stouter torque converter or aftermarket perfomace tranny(ATS or BD) along with the other modifications. That's what I want to do to my truck(2004 2500hd duramax).
  • spademan

    I live in wyoming and winters here are pretty cold. It's not uncommon for the high temperature to be below zero. I run Shell synthetic rotella 5w-40 all year. But 10w-40 or 15w-40 should work all right. Make sure you get a diesel motor oil. And I always warm up my d-max for at least 15 min.
  • stonegstoneg Posts: 47
    Ive got the exact same truck, K&N filter (not the entire intake) already did the leveling kit, 5100's, 285/75/16 BF Goodrich AT TK KO's (had to still trim the front valence a little to keep from rubbing. I did the cat back Banks 4" Stainless Exhaust with the straight thru muffler and the 5" tip. I was having a hard time deciding which programmer to go with also. It was between the Banks or the Edge with attitude. I decided on the Edge for two reasons. (1) I liked the in cab monitor better, and (2)every single person with a D-Max that I met who did install a programmer went with the Edge. I have had absolutely no regrets. I also talked to a diesel specialist (Shivers Diesel)and the Edge was the one he recommended for the D-Max. You are getting some awesome mileage!! I bought mine about 3 months ago, and now have about 6,000 miles, but have NEVER seem mileage like that. Most of my driving is stop and go, but I did level kit 2 days after the purchase, and swap tires within 5 days. Maybe its the tires???(or my heavy foot) My city MPG averages 12.5
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