D-max mileage??

[PHS79]

First off I am not trying to start a Power Stroke vs, Cummins vs Duramax thing with mileage here.

A friend of ours bought a 2006 Chev 2500 HD, CC/SB, 4X4, Duramax/Allison with 97,000 miles on it (I do no know what gear ratio its running). I followed him to the campground, after we had supper and the wives took the kiddos to the playground. He asked me what I got for mileage with my truck on the way to the CG, my display said 10.9mpg towing our 6500lb TT towing at 65mph for the 100 all interstate miles (which I was pretty happy with). He then said "hopefully I will get that", then told me that he has only been averaging 12 mpg empty so far.

When we got back home, he called and said that he got 9.8 mpg towing there 7000 lb TT. I also fueled up and ended up getting 11 right on the head (a best for me). We both traveled the same route at the same speed 65 mph, granted his TT is 500lbs heavier but with his 2500HD Duramax vs my F150 5.4L the MPG dont make sense to me... Then yesterday I talked to him he up on about 500 miles on the interstate running empty and only got 14mpg. I don't know much about the Duramax, I know that the motor has several different versions and that each of them have their little quirks. Is the 06 version poor mileage?

So my question is, with the exception of tuning/intake/exhaust (since thats what I suggested and he wants to keep it stock) what could be causing this bad mileage? Also is there anything that he can do to up his MPG?

[skidoonut]

i have an 05 cc dmax 4x4 and i get 18 city 21 highway and 15 towing. he either has a heavy foot or it is not running right.

[Twisty]

It's the nature of the beast.
"2500 HD, CC/SB, 4X4, Duramax/Allison"
It's heavy, sits high, has part of the 4x4 system turning all of the time, tires (off road, traction) make a difference, etc.
My Dad's Duramax/Allison 1 ton dually 4x4 gets about 12 to 14 hwy and 8 to 11 towing a 5th wheel.
My F150 gets about the same mpg's as yours.

"i have an 05 cc dmax 4x4 and i get 18 city 21 highway and 15 towing."
No offense... but...
difficult to believe, my friend.

[TURBS]

Originally Posted by Twisty

It's the nature of the beast.
"2500 HD, CC/SB, 4X4, Duramax/Allison"
It's heavy, sits high, has part of the 4x4 system turning all of the time, tires (off road, traction) make a difference, etc.
My Dad's Duramax/Allison 1 ton dually 4x4 gets about 12 to 14 hwy and 8 to 11 towing a 5th wheel.
My F150 gets about the same mpg's as yours.

"i have an 05 cc dmax 4x4 and i get 18 city 21 highway and 15 towing."
No offense... but...
difficult to believe, my friend.

08 d max ext cab 4x4
I get 18-21 city/hi way



I'd be very optimistic on 15 towing.

Towing is tba.

[skidoonut]

Originally Posted by Twisty

It's the nature of the beast.
"2500 HD, CC/SB, 4X4, Duramax/Allison"
It's heavy, sits high, has part of the 4x4 system turning all of the time, tires (off road, traction) make a difference, etc.
My Dad's Duramax/Allison 1 ton dually 4x4 gets about 12 to 14 hwy and 8 to 11 towing a 5th wheel.
My F150 gets about the same mpg's as yours.

"i have an 05 cc dmax 4x4 and i get 18 city 21 highway and 15 towing."
No offense... but...
difficult to believe, my friend.

dually's suffer in fuel mileage. sorry to tell you. i also run 285 mud terrain's which helps lower my rpm's on the highway. also the older dmax gets better mileage. i have a friend that owns a trailer dealership and he runs a 06 dually 2wd and he gets about the same as your dad.

[FR28footer]

Have a 2012 Silverado 3500. Pull a SOB that weighs just over 13k. Get 11 to 12 towing and 22 highway.

[Twisty]

I get 38 mpg when I take a pic at the right time.

"I'd be very optimistic on 15 towing."

See above.

[TURBS]

Originally Posted by Twisty

I get 38 mpg when I take a pic at the right time.

"I'd be very optimistic on 15 towing."

See above.

6 days of driving.....
Just took pic and need fuel.
That's also with one day of hauling trailer 30 miles.....
Get over it.

I see you drive a ford gasser it all makes sense now
See below

[SSmbs]

Have towed a 5th with a 2007.5 5.3 gas and 2008 duramax (has dpf pollution control). Mileage with 5.3 and Duramax about the same empty but Duramax 2 mpg better towing. When the warranty (and dpf gone) in a couple of months I expect an improvement. As far as a towing vehicle the Duramax/Allison wins big time over the gas.

[Twisty]

"the older dmax gets better mileage"

"22 highway" from a "2012 Silverado 3500HD"

How far do we need to take this?

[Sgt. Schultz]

I would suggest that your friend start with the basics - fresh fuel filter, oil change, check & replace the air filter as required, if it has not been done change the axle fluids & tranny fluid, a diesel purge would also be a good idea IMHO - DIY DIESEL INJECTOR SERVICE
The following may also offer some suggestions Smoke Tells A Story

[jeeplj8]

Originally Posted by sreddy

I would suggest that your friend start with the basics - fresh fuel filter, oil change, check & replace the air filter as required, if it has not been done change the axle fluids & tranny fluid, a diesel purge would also be a good idea IMHO - DIY DIESEL INJECTOR SERVICE
The following may also offer some suggestions Smoke Tells A Story

Excellent advice!!

[Cajun Po-Boy]

Originally Posted by sreddy

I would suggest that your friend start with the basics - fresh fuel filter, oil change, check & replace the air filter as required, if it has not been done change the axle fluids & tranny fluid, a diesel purge would also be a good idea IMHO - DIY DIESEL INJECTOR SERVICE
The following may also offer some suggestions Smoke Tells A Story

X2

[Soxfan1957]

I have a 2011 2500HD D-MAX. I get around 14mpg city 22 hwy and about 11.5 towing my 5th wheel that weighs about 13K loaded for camping.

[force]

Originally Posted by Soxfan1957

I have a 2011 2500HD D-MAX. I get around 14mpg city 22 hwy and about 11.5 towing my 5th wheel that weighs about 13K loaded for camping.

Just to compare gas v diesel, I have a 2013 GMC 2500 HD Crew cab w/ the 6.0L gasser and 3.73's, and I'm getting no better than 10mpg towing a 5800lb Roo, and my empty city/backroad mileage is around 14mpg.

Granted, I have only 700 miles on the thing, and am trying really hard to evolve from my lead foot days, but I thought it might get better than this. Almost regretting not sticking w/ a half ton.

Almost

[Soxfan1957]

I used to have a 2004 2500HD 6.0L gasser and that thing couldn't pass a gas station.

[Roadie66]

Wow those are some great mileage results! I have a 2011 2500 Duramax with the 6 speed and BEST I get on the highway with about 700 lbs of tools etc at 70 mph is 18mpg. Closer average is 16mpg.
What are you guys doing to get 21mpg??????

[TURBS]

Originally Posted by Roadie66

Wow those are some great mileage results! I have a 2011 2500 Duramax with the 6 speed and BEST I get on the highway with about 700 lbs of tools etc at 70 mph is 18mpg. Closer average is 16mpg.
What are you guys doing to get 21mpg??????

Feather foot!

[jevanb]

Originally Posted by force

I have a 2013 GMC 2500 HD Crew cab w/ the 6.0L gasser and 3.73's
Almost

when did GM start putting in 3.73`s in the HD that was the option in the LD and the only gear set you could get in the HD`s was the 4.10. I ordered and that was the only option, unless you got the dmax

Originally Posted by Roadie66

What are you guys doing to get 21mpg??????

first off keep the stock pizza cutter aired to 80psi, slow starts, take foot off pedal a long way back and coast to a stop

Originally Posted by Soxfan1957

I used to have a 2004 2500HD 6.0L gasser and that thing couldn't pass a gas station.

I had one also and it was a gas hog...


I currently get 16city 22hwy, towing the 12.7k 5er I see 12.5 all day. I am far from stock, execpt for the tires.... replace the rear diff fluid with mobil 1 syn gear lube 70-90w, and also do the front and tcase, your rear is 1qt low from the factory, so do this ASAP 4qts will fill it, the tcase fill with 5w30 syn motor oil 2qts, and front 2 qts of mobil 1 gear lube 70-90w. this should help on the milage. their are a few other things that will help but it will cost about $1500.00 and in the long run pays for it`s self real fast, like EFI tuning, and a exhaust from the turbo outlet back

[Cajun Po-Boy]

Originally Posted by force

Just to compare gas v diesel, I have a 2013 GMC 2500 HD Crew cab w/ the 6.0L gasser and 3.73's, and I'm getting no better than 10mpg towing a 5800lb Roo, and my empty city/backroad mileage is around 14mpg.

Granted, I have only 700 miles on the thing, and am trying really hard to evolve from my lead foot days, but I thought it might get better than this. Almost regretting not sticking w/ a half ton.

Almost

Yep...reason I gave up m '09 2500HD gasser, wasn't impressed with the 6.0 motor after pulling a 9500lb TT for a few years.