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View Full Version : Duramax Milage, What Are You Getting?



hotjava66
04-02-2010, 10:18 PM
I have had a couple Duramaxes, my current one is an 05 SRW Crew Cab. I have had it a few months but havent really done any road trips, gets around 15-16 daily driving. So today I went to get my boat, 3hrs each way, drove around 78 empty there, got 15.5mpg. On the way home loaded 72mph, havent fueled up yet but looks like around 10-11mpg. This is bad compared to my last 2 Duramaxes, I could always pull 18-20 empty and 12-14 loaded (MPG) on the highway. Any ideas, what does everyone else get? Should I be checking for a problem? BTW this is running a Bullydog programmer in Haul/Economy tune, which I have used on the last 2 trucks as well. Power seems fine, just doesnt get the economy im used to. I dont know much history, I picked it up as a repo so it prob. wasnt kept up great but seems ok. Anyone got any ideas or is that normal mileage and I just had 2 really good ones before?

fund razor
04-03-2010, 07:31 AM
Mine is a couple of months new to me. 2006 DRW CC LB.

I am getting 16.5 highway, empty.
According to the DIC anyway. I may haul today. I am interested to see what I get. I am expecting 11-12. No tunes.

I find that it really drops off above 70.

JupiterSunsation
04-03-2010, 08:02 AM
There will be a huge discrepancy here between guys that can do math and the DIC readouts. The DIC is overly optimistic and the correct way to figure it out is to fill it, reset trip odometer, drive it until it is empty and then divide the miles driven by the gallons used. 300 miles on 25 gallons is 12 miles per gallon.....

That being said on my bone stock 03 with 152,000 miles I get 12-13 regularly in 90% city pulling a light trailer and plenty of idling with a/c on. Truck has a decent amount of tools/junk onboard at all times. Best I ever got was 17 driving home from the dealer empty of everything but the dealership paperwork!

BUIZILLA
04-03-2010, 08:37 AM
there's no such thing as *haul/economy*

it's one or the other..

mine would get 15-16 in town and 19.5ish at 78 bobtail

the Diablo plug in set at +65hp picked up 2 mpg all around

Hilltop Kyle
04-03-2010, 09:40 AM
I have the same truck in an '04. I get 16-17 around town empty and 18-19 Hwy running similar speeds. These are hand calculated numbers. The DIC has me getting 22-23 hwy (I wish!). I've replaced the intake, exhaust, and have an Edge Programmer. Unless towing I always run the Edge on the #3 Drive setting (+75hp).

hotjava66
04-03-2010, 02:44 PM
my numbers are all hard/hand calculated. the tune im running is the tow tune, 1st stage lowest program. checked my tow mpg and it was 10.5, boat/trailer/full fuel probably 9000lbs. im a little disappointed, my 03 did quite a bit better, but i did have an upgraded intake and exhaust, and was a standard cab. i know if you keep under 2000rpms you can do a lot better but i just cant drive that slow.

Tyler83
04-03-2010, 03:10 PM
Kinda a little off topic here but I got a 06 2500 crew cab from what I understand they have 25-26 gallon tanks but I have never been able to get more than 21 gallons in it, and that is filling it to the neck after running with the low fuel light on for awhile.

hotjava66
04-03-2010, 04:15 PM
Kinda a little off topic here but I got a 06 2500 crew cab from what I understand they have 25-26 gallon tanks but I have never been able to get more than 21 gallons in it, and that is filling it to the neck after running with the low fuel light on for awhile.

mine never takes more than 22 and thats if I run it on empty for a while

JupiterSunsation
04-03-2010, 04:27 PM
Kinda a little off topic here but I got a 06 2500 crew cab from what I understand they have 25-26 gallon tanks but I have never been able to get more than 21 gallons in it, and that is filling it to the neck after running with the low fuel light on for awhile.

My 03 crew cab got 25.6 gallons added today........26 gallon tank is what my truck has. The long bed trucks have 31 gallon tanks which would be nice!

Tyler83
04-03-2010, 05:44 PM
My 03 crew cab got 25.6 gallons added today........26 gallon tank is what my truck has. The long bed trucks have 31 gallon tanks which would be nice!

Yea it sure would be!

endeavor1
04-03-2010, 06:19 PM
08 D-Smack, PPE hot plus 2 ET running on + 140hp.
Empty in town -15
Empty on highway 16.5
Loaded wth the Black Thunder - 10

Also, I haul ass everywhere, 80-90 on the highway loaded or not so take that into acct. :sifone:

sweet addiction
04-03-2010, 09:19 PM
Damn, I need to get me one of those. I have to pay the tax man $$$ this month so I may get one for Christmas this year. My truck gets like 12 or so with the boat in tow, 17ish on the highway 18 if I am easy but I drive like endeavor does so my mileage is crap.





08 D-Smack, PPE hot plus 2 ET running on + 140hp.
Empty in town -15
Empty on highway 16.5
Loaded wth the Black Thunder - 10

Also, I haul ass everywhere, 80-90 on the highway loaded or not so take that into acct. :sifone:

jwurl
04-03-2010, 09:26 PM
I have a 05 GMC with a Banks 6 gun tuner,exhaust,and intake. I average 16 in town. 18.5 on the highway running 70mph and 14 on the highway towing a 9K lb boat. Jeff Wurl

fund razor
04-04-2010, 06:38 AM
There will be a huge discrepancy here between guys that can do math and the DIC readouts. The DIC is overly optimistic and the correct way to figure it out is to fill it, reset trip odometer, drive it until it is empty and then divide the miles driven by the gallons used. 300 miles on 25 gallons is 12 miles per gallon.....

That being said on my bone stock 03 with 152,000 miles I get 12-13 regularly in 90% city pulling a light trailer and plenty of idling with a/c on. Truck has a decent amount of tools/junk onboard at all times. Best I ever got was 17 driving home from the dealer empty of everything but the dealership paperwork!

Nice way to put it.

fund razor
04-04-2010, 06:40 AM
My 03 crew cab got 25.6 gallons added today........26 gallon tank is what my truck has. The long bed trucks have 31 gallon tanks which would be nice!

The 34 gallon that many of us have is nice, also.

On topic: did tow yesterday. Got 12 on the DIC going 65 hwy. (for what that's worth) Didn't have the variables on hand to do the math, although I can do the math. :)

hotjava66
04-04-2010, 07:36 AM
The 34 gallon that many of us have is nice, also.

On topic: did tow yesterday. Got 12 on the DIC going 65 hwy. (for what that's worth) Didn't have the variables on hand to do the math, although I can do the math. :)

I really miss my bigger fuel tank, having to fill up every 300 miles is a pain, my old Duramax with the big tank I could sometimes make close to 600 miles

JupiterSunsation
04-04-2010, 08:23 PM
The 34 gallon that many of us have is nice, also.

On topic: did tow yesterday. Got 12 on the DIC going 65 hwy. (for what that's worth) Didn't have the variables on hand to do the math, although I can do the math. :)

Fund

I just laugh when guys either post or tell you at a gas station their diesel gets 22-24 MPG.......then the BS begins, like ran 85 all the way up I95 from FL to GA, pulled my 30 ft camper like it wasn't even back there and had 4,000 lbs of gear in the bed.......:eek:

The trucks are more efficient than their gas equivalents but everything has its limits!

endeavor1
04-04-2010, 09:20 PM
Fund

I just laugh when guys either post or tell you at a gas station their diesel gets 22-24 MPG.......then the BS begins, like ran 85 all the way up I95 from FL to GA, pulled my 30 ft camper like it wasn't even back there and had 4,000 lbs of gear in the bed.......:eek:

The trucks are more efficient than their gas equivalents but everything has its limits!

+1 :cheers2:

OldSchool
04-04-2010, 09:48 PM
I drive 62 miles each day and about 40 of then are highway miles. the rest are through the city. I get 16.5 MPG's with my 2005 lly Duramax 2500. It never changes. About 19-20 on the highway trips. That's running 70-75.

hotjava66
04-04-2010, 10:29 PM
I drive 62 miles each day and about 40 of then are highway miles. the rest are through the city. I get 16.5 MPG's with my 2005 lly Duramax 2500. It never changes. About 19-20 on the highway trips. That's running 70-75.

thas whats bugging me, the 15 empty on highway, my other ones were closer to 18-19.

509SC
04-04-2010, 10:54 PM
I recently got an 06 SRW CC, drove to Manning in Michigan last week and got 18 empty and 13.4 returning with a #2250 trailer. Trip was 300 miles each way most of the time I ran 75 and mileage was hand calculated. I have a short bed with the 26 gallon tank, has anyone upgraded to a larger tank or done an auxilary tank, I would like to look into that. The range isn't great towing and I hate to be forced to stop in busier areas just because I need fuel. It would be nice to say I'll stop in another 50 miles in a quieter area. Steve

fund razor
04-05-2010, 06:45 AM
Fund

I just laugh when guys either post or tell you at a gas station their diesel gets 22-24 MPG.......then the BS begins, like ran 85 all the way up I95 from FL to GA, pulled my 30 ft camper like it wasn't even back there and had 4,000 lbs of gear in the bed.......:eek:

The trucks are more efficient than their gas equivalents but everything has its limits!

Well, I pulled my boat less engines was 6000 lbs and I didn't even feel it back there. :leaving:

I always tell those guys that I can idle at .34 gal per hour. And that I can do it all day. :)

Quinlan
04-05-2010, 07:52 AM
I have an 07classic SRW 3500 CC I get 12 to 13 Hand calc. that is mix of hiway and city. When I tow the Cig long hauls I am at 12.
I have the Bully Dog and exaust. Also running 305.55.20s so I think my MPH might be off a little.
Also got the Larger tank from Transflo ( I think) 55 Gal BEST money spent. Now can go twice as far on fillup. :cheers2:
O and did I say I DRIVE it!! :driving:

JupiterSunsation
04-05-2010, 07:54 AM
I recently got an 06 SRW CC, drove to Manning in Michigan last week and got 18 empty and 13.4 returning with a #2250 trailer. Trip was 300 miles each way most of the time I ran 75 and mileage was hand calculated. I have a short bed with the 26 gallon tank, has anyone upgraded to a larger tank or done an auxilary tank, I would like to look into that. The range isn't great towing and I hate to be forced to stop in busier areas just because I need fuel. It would be nice to say I'll stop in another 50 miles in a quieter area. Steve


Steve

Welcome to SOS.........there is a company that makes a bigger tank to replace the factory tank. It is about 20 gallons bigger and sits in place of the factory tank. From a side profile view it can be seen hanging below the bottom of the truck, not terrible but an inch or two lower. Price wasn't terrible either, just looked to me like a hassle to install.

fund razor
04-05-2010, 08:11 AM
Steve

Welcome to SOS.........there is a company that makes a bigger tank to replace the factory tank. It is about 20 gallons bigger and sits in place of the factory tank. From a side profile view it can be seen hanging below the bottom of the truck, not terrible but an inch or two lower. Price wasn't terrible either, just looked to me like a hassle to install.

Yeah... welcome for sure. :cheers2:

I think that I saw some info about that tank on dieselplace.com. I'll bet it would be an easy search.

TANTRA
04-05-2010, 08:35 AM
My 08 gmc 2500hd gets 12mpg in town and 16mpg highway.not that good but i only drive 8 miles to work.

Kelly O
04-05-2010, 09:04 AM
08 Chevy DMax, 3:73 Rears (6 spd. Auto) 12 mpg around town, 16 on highway, 10 mpg towing 12,000 lbs of boat and trailer.

Dealer claimed it would get better once "broke in". Must be 28k miles not enough to break it in yet !:driving:

They sure are much better for towing and the tow mileage is almost double what I used get with the 6.0 gas motors. Apparently delete pipes and programmers can get mileage back to previous models' levels but having warranty is nice too.

Next generation of DMax will have two tanks to fill, one for fuel and one for the magic pollution cancelling fluid.

Hilltop Kyle
04-06-2010, 04:45 PM
08 Chevy DMax, 3:73 Rears (6 spd. Auto) 12 mpg around town, 16 on highway, 10 mpg towing 12,000 lbs of boat and trailer.

Dealer claimed it would get better once "broke in". Must be 28k miles not enough to break it in yet !:driving:

They sure are much better for towing and the tow mileage is almost double what I used get with the 6.0 gas motors. Apparently delete pipes and programmers can get mileage back to previous models' levels but having warranty is nice too.

Next generation of DMax will have two tanks to fill, one for fuel and one for the magic pollution cancelling fluid.

Mine didn't really "Break In" until I hit 50K. I noticed an increase in mileage and performance when I got over 50K. You may still see an improvement.

Flat Rate
04-10-2010, 04:52 PM
the lly gets the worst mileage of all the duramaxs only was in 04.5 -05 trucks the earlier lb7 didnt have the emmisions the lly was the first smog motor then 06 got the lbz and does much better.

BUIZILLA
04-10-2010, 05:45 PM
the lly gets the worst mileage of all the duramaxs only was in 04.5 -05 trucks the earlier lb7 didnt have the emmisions the lly was the first smog motor then 06 got the lbz and does much better.
that's the first time I heard that....and I work on them daily.... my 06 was an LLY with an LBZ computer.... mileage was excellent....

Flat Rate
04-11-2010, 11:28 AM
that's the first time I heard that....and I work on them daily.... my 06 was an LLY with an LBZ computer.... mileage was excellent....

We have all of them and the 05 is the worst of the bunch it has the same exhaust and chip as the 04 and also has a egr block off plate and no cat because the egt were way high when towing. it got better but 4mpg less than the lb7. lbz is a great set up. Can u put a lbz computer on a 05 lly truck?

BradH
05-10-2010, 11:39 AM
'06 ex cab 260K had 21-22 on the highway by hand calc. Borrowed truck, could not believe it.

afr
05-10-2010, 12:41 PM
i get around 23 mph gallon with mine but
the pos is a lemon and Chevy wouldn't fix it
ever sense new it goes into some kinda limp lemon mode
first time it happen i didn't think nothing of it cause it didn't do it again
then it finally got worse so i took it in they put new injectors in it what a horror story that is the thing leak fuel all over my boat for months they couldn't find the leak then finally it filled the whole crank case full of diesel and they finally found it
now there telling me my injector pump is bad and the limp mode is cause of low fuel pressure and they want 1500 dollars to fix it first off i would never let them touch my truck again period they broke my air box and the dip stick the last go round miss aliened clamps etc etc
so now i just live with a 40 thousand dollar truck that is only good to go to and from work
other then that i love it
lol