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Chevy Silverado and GMC Sierra Duramax Fuel Mileage

506 messages,  Last post on Nov 30, 2009 at 5:21 PM

You are in the Diesels Forum. Your Host is kcram

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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#429 of 506
Re: Bad Mileage. Any suggestions? [jmcgoff] by jerrydock
Jan 07, 2009 (4:36 am)
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Replying to: jmcgoff (Oct 25, 2008 7:35 pm)

There is nothing wrong with your truck. Some get better mileage than others and some need to get over 20,000 miles on them before they begin to improve. I have over 50,000 on mine now and switching to Amzoil synthetic diesel grade oil helped get another 1-2 mpg. Good luck. Enjoy the truck and stop pestering the dealer; their mechanics don't have a clue anyway.
#430 of 506
Got one! by pete59
Jan 07, 2009 (8:00 pm)
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#431 of 506
Got one! by pete59
Jan 07, 2009 (8:13 pm)
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My first post was back at #312. I asked about fuel mileage on a long bed two wheel drive diesel with the Allison tranny. Since then I purchased a 2008 Silverado four wheel drive crew cab. I am commuting the 110 miles a day as stated back then. I was hoping to get at least 20mpg to match my old two wheel drive Ford and hopefully better down the road after break in. My commute is about 30 miles of hills and 20 fairly flat. Most days I get right at 20 mpg. Some days a little worse but I have found it seems to make a difference as to the fuel you buy and humidity or rain seems to make a difference also. In the summer I trailed a 16 foot boat behind my 30 foot fifth wheel. On the average ( Interstate ) I got 11.5 mpg. I now have about 20,000 miles so it still early.... I am a moderate driver and stay close to the speed limit. It's amazing how much you watch the instant on-board MPG. and how it effects my driving habits.
#432 of 506
Duramax fuel mileage by axle1
Jan 21, 2009 (6:49 am)
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Is the LB7 duramax motor better than the LLY motor. From my experiences it is far better.
#433 of 506
Duramax Milage by jbull454GMC
Jan 25, 2009 (5:20 pm)
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I have recently purchased a 2008 GMC 2500HD with a Duramax. I have to admit, at first the mileage was not good. Roughly 14 mpg around my normal driving range. and about 17 on the highway. I work for a Chevrolet dealership. (No I did not but a chevy, I think the GMC looks better) I looked up the trucks history on a GM web site. I found it had been sitting for a year. Upon finding this out I changed the oil the following day. I noticed about a 1-1.5 mpg increase. Also as I have put miles on the truck I have noticed the power increase. Therefore break in is a big thing with this engine. I've seen that keeping the RPM's below 2000 in normal driving help alot too. I did get about 21 mpg on a small trip I took with it on the highway after changing the oil also. I am switching to Amsoil at about 10,000 miles to see how it does there. There is one thing I have noticed that makes the fuel mileage drop drastically, and that is the regeneration system for the particulate filter. The mileage dropped to between 12 and 13 mpg. Thank you federal government for that...Any input on MPG tips would be greatly appreciated. Also if anyone wants to know any thing about their GM truck feel free to contact me. I look forward to reading more on this site.
#434 of 506
Re: considering chevy [rbb39] by jbull454GMC
Jan 25, 2009 (5:29 pm)
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Replying to: rbb39 (Aug 10, 2008 1:41 pm)

I work for a chevy dealership. As for the 05-07 duramax no recalls, as the older models had an injector recall. The newer models seem to be doing fairly well so far as for repairs. Mileage is about 15-20 depending on driving. Stay away from the new body style 2007 and a half on up. They do not have the particulate filter which as a regeneration system that activates to burn off the soot build up. When this occurs mileage drops considerably. I have a 2008 GMC and I've been down this road with it. Good luck with your search!
#435 of 506
Re: Duramax Milage [jbull454GMC] by losman54
Jan 25, 2009 (5:34 pm)
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Replying to: jbull454GMC (Jan 25, 2009 5:20 pm)

I agree I like the looks of the Sierra a lot better than that dumb chrome over plastic front bumper. I'm interested in knowing what kind of Amsoil oil are you using in your Duramax. I just traded my 2002 Silverado and got a new GMC Topkick and I'm getting 13-17 city/hwy not bad.
 
One thing that I had in my Silverado that I would recommend is a K&N air filter, it will add 10-12 HP, and as you know your will get better MPG with more HP, and colder air. It's pricey but it's the last you will have to buy!
#436 of 506
Re: Duramax Milage [losman54] by jbull454GMC
Jan 25, 2009 (5:44 pm)
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Replying to: losman54 (Jan 25, 2009 5:34 pm)

That bumper is what really turned me off. I will probably be using 5W40 Amsoil. It, right now, is the only one formulated for the new LMM engine. I don't know if K&N offers a filter for the LMM engine. The current filter that comes factory is made by Donaldson. Donaldson is recomended by Amsoil actually. I'm not sure I want to add any more power to that engine! It could get me in trouble as it is, and its getting quicker with break in. I will definely keep that in mind though. Thanks!
#437 of 506
Re: Duramax Milage [jbull454GMC] by losman54
Jan 25, 2009 (5:52 pm)
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Replying to: jbull454GMC (Jan 25, 2009 5:44 pm)

you can go on to their site and enter yr/model and if they have one it will come up. THX for the info on the Amsoil...have you seen any MPG as a result of using Amsoil?
#438 of 506
Re: Duramax Milage [losman54] by jbull454GMC
Jan 25, 2009 (6:38 pm)
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Replying to: losman54 (Jan 25, 2009 5:52 pm)

Okay, I'll give it a look. Thanks for the info there. As for my currant truck I have not put it in yet. Its not boke in. As for other trucks, which were all gas, yes. Believe this or not. I have an 86 Chevy crew cab dually, 454, 4 wheel drive. I got almost 16 miles to the gallon on a trip to North Carolina with it. It wasn't my idea to take it, that was a now ex's idea. Plus my other vehicles I have put it in have increased in mileage too. I am looking forward to see how it does in my Duramax.

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