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Chevy Silverado and GMC Sierra Duramax Fuel Mileage

425 messages,  Last post on Sep 02, 2008 at 5:45 PM

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What is this discussion about? Chevrolet Silverado 2500HD, Chevrolet Silverado 3500, GMC Sierra 2500HD, GMC Sierra 3500, Diesel, Fuel Efficiency (MPG), Truck

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#416 of 425 Re: BAD FUEL MILAGE! [losman54] by captbilly Jul 30, 2008 (3:05 am)
Replying to: losman54 (Jul 25, 2008 7:00 pm) If it sounds too good to be true....it probably is.   You can clean your injectors but after that, it is hard to gain enough economy from a tank of fuel to cover the cost of the additive. Bottom line...If you want excellent fuel economy buy a little hybrid car. If you want a big ole chevy truck for work- pay at the pump. I gotta go...my truck is running.
#418 of 425 diesel additive / dieselhead magazine tests? by elias Jul 30, 2008 (5:31 pm)
many tdi geeks report slight mpg increase when adding powerservice or other lubricity additive. could be the placebo effect. i've certainly noticed smoother TDI operation & startup in winter when I use the winter/whitebottle poweservice but i didn't bother with it even during subzero temps last winter.   haven't any of the diesel/truck mags done tests with the new duramaxen on the track at 65 mph with modded software / disabled fuel-wasting "regeneration" ? wouldn't it be an easy test? well, easy for me to say! Replies to this message: losman54 (Jul 30, 2008 7:06 pm)
#420 of 425 Re: diesel additive / dieselhead magazine tests? [johnnyell] by losman54 Jul 30, 2008 (7:06 pm)
Johnny...please leave all of us alone ...get a real job or go find yourself a street corner to sell your stuff and stop trying to sell this stuff to people who don't care.
#421 of 425 considering chevy by rbb39 Aug 10, 2008 (2:41 pm)
I am looking to purchase a truck soon, and I dont know what to buy. I am looking at maybe an 05-07 Duramax 2500HD 4x4. Anyone know of any mechanical or recall problems that these trucks have had. What about fuel mileage, good or bad?
#422 of 425 Re: BAD FUEL MILAGE! [dravera] by maddogmurf Aug 10, 2008 (6:12 pm)
Replying to: dravera (Jul 25, 2008 9:41 am) I just had the ECU update put in my 07 sierra, 2500HD, long bed crew cab. Things were all geeked up on the mileage indicator etc after I went from 245 (5ply) to 265 (10 ply) tires. The dealership stated they would not update the computer for the increased tire size.....tough on them at least I will get a few more miles out of the warranty as I'm going to go to 285s real soon, the 10 ply helped immensely with ride under load. I drug a 15,000 lb load 800 miles and got 18 miles to the gallon.....I was sweating as the fuel consumption stated that it was using way more than it was with the new tires.....but the fuel performance is sometimes great, sometimes sux though I have never gotten less than 16 without a lod or 11 with a 15-20,000 lb load.....best time to drive and drag a load is definitely at night when it's cool. In the heat of the day with a head wind it can definitly chow down on the diesel. I've gone from Colorado Springs to KC on 30 gallons of fuel and another time made it to Hayes on 3/4 tank, then from Hayes to Joplin on 2/3 tank and changed nothing except lost the head wind and day went to night.....we'll see how it operates with the new ECU update. I did get a Diablo chip for it but I have to do some tests, like install it properly. The guys who put it in initially didn't follow the instructions.....was not impressed as the truck got noisy with the 80HP boost and acted goofy with the 60HP boost....but bottom line, it wasn't installed properly.....so we shall see.....yea I know about warranty issues and chips......but someone purported better mileage with the chip if you keep your foot out of it. I also found by changing the fuel filter at 50% life and cleaning the K&N at the same time helps as well.....that could be why I got such great mileage with a load on this trip. Even with 26000 miles it runs quieter than any other truck next to it......and ain't had a sports car yet take me off the line. It does ride like a Cadi, run and handle like a porsche, and work like a truck.
#423 of 425 Re: DURAMAX FUEL MILEAGE [gagrice] by maddogmurf Aug 10, 2008 (6:21 pm)
Replying to: gagrice (Sep 19, 2004 3:01 pm) I have gotten as high as 22mpg. Just had an ECU update and got 18 plus MPG over 790 miles with a 15,000 lb load.....go figure.....the mileage is a weird creature on the duramax.....I have gone to replacing the fuel filter at 50% and cleaning the K&N at the same interval......I also change the oil at 100 hours, 3,000 miles or 30% oil life left, which ever comes first. I have noticed better mileage tends to occur with night driving when the temps are cooler.
#424 of 425 07 Duramax by maddogmurf Aug 10, 2008 (6:37 pm)
I bought my 07 in June 07.......I love the truck.....pulls the mountains here in Colorado as though it were on flat ground.   At first the mileage sucked then after about 10000 miles things began to improve.   To date I have gotten as high as 22 on the highway (I-70) doing the speedlimit of 75-65. Never gets above 2000 rpm at 75 mph except when accelerating.   I have had really bad fuel performance with a head wind. I have gotten as little as 11 MPG with a 15-20K load. This last trip though I had at least 15000 on and got 18 MPG after upgrading to 265 10 ply tires and having the dealership install the new ECU updates. I had to keep track of fuel consumption after switching to the 265 tires as the dealership will not update the module for me for the new tire size.   The jake brake works awesome. The thing tows like there is no tomorrow and runs like a sports car, rides like a Cadillac as well.......I bought a Diablo chip and the jury is still out as I found that the guys didn't install the chip correctly. Air bags are a must for big loads.....I wonder just how much it would tow as I have had some loads on it and it just keeps going whether sea level or mountains......   I did find that a new fuel filter at 50% fuel filter life.....cleaning the K&N air filter at the same interval, and changing the oil at 30% life remaining, 3000 miles, or 100hours (whichever comes first) also helps. Long trips go better at night and I'm hoping this last trip with a load is an indicator of future fuel mileage performance.
#425 of 425 Re: 2500HD Slow Acceleration [jwashin] by evanderm Sep 02, 2008 (5:45 pm)
Replying to: jwashin (Sep 24, 2004 7:48 am) Hello my name is Evander, I myself just bought a 01' Duramax and i have the same exact problems... Im Furious i even noticed some blue smoke coming from exhaust and the mechanic said its all due to my fuel injectors. I do not have the $4,000 to fix what they are saying is the prob.So if you find out something new would you please contact me personlly.evandermartinezyahoo.com And theytold me that the extended 7yr warranty expired on 5-11-08 other wise they would warranty it ..

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