helo all,
i just joined this board after watching it for a few days. im looking for some honest opinions. i am looking into buying a 2003 sierra with a duramax, witha 6 speed, 4 wheel drive, dont know the diff ratio. wondering if anyone has something similar, what i can expect as far as quality, fuel milage, or any problems anyone has seen. im sure it will be a major step up from my 86 3/4 ton with a 350, but just trying to get a feel for what to expect. any help is greatly appreciated


-tom-

I've got a 2003 Chevy Duramax with Allison, Crew Cab long box.
I get 19-21MPG running highway at 72MPH and 16-18MPG pulling the boat on the highway 80% with about 20% around the cabin and back roads.
Around town mileage-all short trips are as low as 14MPG.


They are nice trucks!


I would only expect better fuel economy with a manual as the automatics leech more power from the engine.. But then again all these trucks differ on what kind of mileage they get.

NO offence to anyone looking at the trip computer for thier calculations, but the reality is, these trucks don't get the mileage that most claim. I have done some serious research, and also kept every fuel receipt since new.


One factor in your MPG's will be whether you have injector problems. bad injectors will cut your MPG's by 20 or more percent. Here are my averages, before having the injector problem I have now. (still waiting for the backorder to clear)


Strictly Around town unloaded, 12-14 - Strictly Highway at about 70 MPH, = 16.5-19. Best I ever did was 20.3.


Towing is a different animal. When towing (see my sig below), I get about 8.5 to 10.5. The best I ever got when towing was 11. And that is/was the best, period. Average is 9.5, although I hate to admit it.


I hear stories of folks getting 17-19 while pulling 15,000 horse trailers, but I don't believe it. They are probably looking at their DICs when going straight and down hill. SO, you will see several posts, and I can only speak for mine, but I can promise you, my numbers are dead accurate. And no fluff added! Just the truth and nothing but the truth!!


Good luck........

Whaping 18,000 miles on this girl, pulls a 36' foot Alfa where ever I ask it to. My milage is simular to the others, about "Double" of a gasser. Deturmine what you want and go for it.





Idahofox

I understand where you are coming from about the trip computer.

But when traveling with the Duramax cross country my trip computer was VERY accurate.. When going for fuel, I always fill it to the brim. Quite a few times I've filled up and in the menus it will say something like 17.1 gallons burned and I'll put in 17.1 or 17.2 gallons of fuel and its full..
Pretty accurate.

But I get the kind of numbers listed above by hand or by looking at the computer. Its been pretty accurate.

Bobcat,


I wish I could say mine was as accurate. I have been in several times to the dealer, complaining about how inaccurate mine is. Of course, I use a calculator to measure my MPG's and I know the Speedometer and Odometer are accurate, because I have done extensive testing with a GPS. And I've used more than one GPS unit as well.


My problem is that I let this stuff bother me! Maybe because I had to pay for it when I bought it, and no one told me it would be 2 gallons off when filling up. You can guess how 'off' the rest of the DIC calculations would be at that point!


Glad yours is good! I hate mine!

Although I have a 2004.5, I have access to a 2003 with the Allison. Overall, I think the quality of both trucks is excellent.

Duramax weak points:
- Possibly fuel injectors. There are posts from 2003 owners reporting injector issues. Before buying, have a GM dealer run a scan on the injectors. They can also check the dealer service history, given the VIN number.

- Air conditioning performance is poor when the outside temp gets over 100 degrees. GM changed the A/C system for whatever reason starting with the 2003 model, and it was not for the better. GM has just come out with a new accumulator to fix the problem for the 2004 and I think the 2003. Again, check with a dealer for details.

- 6 Speed: There are posts on this site from 6 speed owners reporting problems. Since I have the Allison, I have not followed this issue in detail. I think it is with the fly wheel. Hopefully a 6 speed owner will post any concerns.

-Fuel Mileage: I think a lot is just the luck of the draw. There is a large mileage variation reported on this site. Factors are the way the truck is equipped, driving conditions, fuel, etc. But after reading at least 100 mileage reports on this site, I think there is a large variation between individual trucks. In my personal experience, the particular 2003 mentioned above has gotten almost 5 more mpg than the 2004.5 under the same driving conditions. The 2004.5 gets ok mileage, but for some reason, this particular 2003 gets exceptional mileage. I have no idea why.

The 2003 brochure only shows a diff. ratio of 3.73 for both the 2500HD Duramax manual and auto.

If everything checks out clean on the truck, I think you will be very happy with it. Even though the fuel injector issue is an expensive repair, it appears to be a problem for only a small percentage of all the trucks on the road. Again, it is the luck of the draw. The 6 speed problem may be an issue. Do a search on this site for issues with the ZF S6-650 manual. It looks like the A/C issue is about to be a non-issue.

I hope it works out for you. I sure am glad that I bought mine, it is a great truck. That's my "honest opinion".


Edited by: BH in AZ

Post the VIN# and one of the Techs may check it out for you for any past problems that were taken care of by GM.

I have a 03 silverado reg. cab 4X4 6spd and love it. I get around 20 to 21 mpg on the highway running 65 mph with the calculater and it is close to the dic. BUY IT !!!!!! Edited by: gearhead

I have a 2003 6 speed and love it. I always calculate mileage by hand and get 19-20.5 average unloaded. (Most of my driving is highway so I'm sure that raises it a little). Just put on larger tires a few days ago so we'll see how that effects mileage and towing.


When I tow my heavy stuff I'm 17,300 gross including an overhead camper and get 12 mpg going from Denver to Moab UT. Without the camper it's about 2 MPG better and according to friends with the Allison, the manual seems to do better on mileage by 1-3 MPG. I still wouldn't trade my 6 speed for an auto, guys I run with towing roughly the same weight with the auto fall back on the passes. The flywheel is the number one concern with the 6 speed but it's covered under the engine warrantee for 100k and GM is supposed to have a fix for it soon. If they don't I'll buy an aftermarket billet one if it fails after the 100k and they havn't fixed the problem. My truck has 35K on it and no problems yet even with a LOT of hard towing. I've got the squeeky clutch pedal but it doesn't bother me so I'll just have the dealer document it and if they develop a fix I'll do it. This is BY FAR the hardest pulling, hardest working truck I've ever owned. Compared to the new Powerjoke and the Dodge these truck seem to have far less problems even with the early model injector issues. Mine was one of the first 2003 trucks off the line so we'll see if the injector gremlins carried over at all. Your going to love the truck without a doubt.

thanks for all the help, im sending the wife to look at it tomorrow while im at work, ill tell her to get the VIN number and let ya'll know what the truck looks like.

-tom-