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I just received my new '06 Duramax w/ 6 sp. Allison, can any tell me what kind of fuel milage I should receive? So far I am getting 13.5 MPG around the city. I have been reading through the internet that people getting 17-21 mpg in the city. Does this come in time after a certain amount of Driving?
 

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If you are doing true city driving, you probably won't get too much better than that. I don't think you would be having winter blend fuel down there in TX, so you can't blame that. You will find out that a good majority of people don't hand calculate their fuel mileage, they just go by the DIC. This becomes a problem when you start adding a programmer, which throws the DIC off even more. If I would go by my DIC, I would be getting about 24-28. In actuallity I usually get 17-19. During the winter up here I get anywhere from 10-14 depending how much I drive into town (21 miles one way). Do you have a dually? As far as what you are supposed to get....I don't know for sure, but my LB7, I get anywhere from 17-19 on with mostly highway driving. LB7s did get better mileage than the LLY, but the LBZ hasn't been out long enough to tell. Of course a diesel engine isn't really considered "broke in" until around 25,000-30,000 miles.
 

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Thanks OB_1JR for the information that you have given me. I will keep track of the MPG as I drive it more. I was told by a friends friend that I need to change the oil to a better grade after driving it 3000 miles, any truth to that?
 

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Most people change their oil over to synthetic then I believe. I haven't heard of that though. I bought my truck slightly used, so I never got to deal with the break-in period. The more you drive it, the better it shouldget over time though.
 

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I noticed a slight increase in mileage when I got over the 10k mark..and from what i hear when you get over 20-25k that will should show you the best MPG you'll get. Do you have a 2500 or 3500? there is a good difference in mileage...
 

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I have a '06 2500 HD 4x4 w/ LBZ D/6sp. Ally. that I just picked up last Friday. Question:help ? When should I do my first oil change? and which oil is best to use? Shell Rotella T, Mobil 1 syn., Chevron Delo, Etc? Any help that you can offer would be great!
 

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I have had my 2500HD with Duramax and 5 speed Allison since it was new. Got 43,000 on it now. I always use a good grade of 15W40 just as the book recommends. I took it back to the dealer for the first oil change at their recommended mileage. They will check everything else while you're in so you will have fewer problems. These trucks all have 3:73 gears - even the 3500s. They all should get around 17 -19 COMBINED city and highway. I get up to 21 on long trips unloaded. Because I live about 10 miles from the city I don't know what a good average would be for city driving. The only things that make a big difference in fuel mileage in these trucks is #1- your driving habits. If you are like I was at first you won't be able to resist quick starts away from lights and strong accellerations up the freeway onramps. These things excellerate amazingly well and are F-U-N to drive. So, you get what you can expect. #2-The other main thing may not have so much effect because the torque is there in all of the Durmaxes. That would be the gross weight of your truck. The lightest one, a 2500 HD extended cab short box is about 1000 lbs less than the 3500 HD crew cab long box 4wd. If you tow a camper or other trailer with high wind resistance expect your mileage to drop accordingly. Terrain, flat or hills, will dictate too.

If I were you I wouldn't change to synthetic oil until about 30 to 40 thousand miles. The reason is that diesels wear a lot slower than gas burners do. You want to make sure that you get it good and broke in before you switch or else you open up a new can of worms all together. Generally, it's better to stay with the same grade and brand all the way.
 

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MRTruck said:
I just received my new '06 Duramax w/ 6 sp. Allison, can any tell me what kind of fuel milage I should receive? So far I am getting 13.5 MPG around the city. I have been reading through the internet that people getting 17-21 mpg in the city. Does this come in time after a certain amount of Driving?
i get 20.5 at best empty,12 at worst loaded(about 10,000 lbs)
 

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I have the '05 Durapig, it is just that a fuel hog. I am extremly disappointed in the mileage. I get 13-15 in town, 17-18mpg under 62mph. A guy I know has an '03 and gets 22-23mpg on the highway. I made a big mistake buying the Chevy diesel.KY
 
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