MPG Chev 2500 HD - Montana Owners Club

bkirk · 03-27-2008, 03:57 PM

It seems like everyone is getting better fuel mileage than I do. I have the 2006.5 2500HD 6.6 Duramax CC (first diesel)and I am getting about 16 MPG eveyday and 10 pulling. I bought the truck new and just turned 20,000 on her. I did take off the small 245x70x16 tires and put a set of 285's (E class)on her. Don't like the smaller tire. So I figure I lost a mile or so to the gallon from that, but don't think it should be much more than that. So, can anyone advise what might be costing me fuel mileage ? I changed the fuel filter at 12,000 miles. Help?

exav8tr · 03-27-2008, 04:12 PM

bkirk, I have an '05 2500 D/A and get about 14-15 without pulling and anywhere from 8.5 - 10 while pulling my 3400. Yours seems ok for that truck, in my humble opinion.......

SlickWillie · 03-27-2008, 04:15 PM

Quote:

quote:Originally posted by bkirk

It seems like everyone is getting better fuel mileage than I do. I have the 2006.5 2500HD 6.6 Duramax CC (first diesel)and I am getting about 16 MPG eveyday and 10 pulling. I bought the truck new and just turned 20,000 on her. I did take off the small 245x70x16 tires and put a set of 285's (E class)on her. Don't like the smaller tire. So I figure I lost a mile or so to the gallon from that, but don't think it should be much more than that. So, can anyone advise what might be costing me fuel mileage ? I changed the fuel filter at 12,000 miles. Help?

Sounds about right to me. I have gotten close to 20mpg, but that was driving about 55. On long runs empty, I can average 18mpg running 65 or 70, but short trips cut that down. I've gotten from 9 to 12 towing, varying with wind, terrain, and speed. Mine is 4 X 4, and I believe the 2WD will average a little better.

I'm curious how the 285's do. IIRC I read on the Allison site that 285's or larger could cause problems shifting into OD while towing. I want to go to larger tires, but want the wider rims first.

Montana Sky · 03-27-2008, 05:17 PM

Your motor has not even broke in yet. I did not see my 21/22 mpg highway until I had over 45,000 miles on the truck. Just ran over to Chicago for easter last weekend and averaged...23.7 hand calculated. I believe that you have the LBZ Duramax and they along with the new LMM are not getting the mileage that the LB7 is.

ChuckD · 03-28-2008, 03:53 AM

I have a 2006 Duramax/Allison and drive 13 miles to work, according to the Driver Information Center I get between 14 and 15 MPG winter and 16 and 17 MPG summer. I drive an average of 55-60 mile per hour on the open road. I see some here getting better but I only have 29,000 mile and I do expect it to improve. This winter with the high fuel prices the difference is money.

Clyde n Deb · 03-28-2008, 03:59 AM

The computer needs to be reprogrammed to correlate with the changed tire size. You may be traveling farther than you think. 265 tires are more than enough tire for these trucks, and can readily be used on the stock rims.
My mileage varies greatly depending on driving style and speed.

HughM · 03-28-2008, 04:28 AM

Yours is about the same as my LMM. 15 around town and 20-21 Highway. Towing 11 sometimes 12 mpg. But I'm in Florida where there's no mountains.
My tires I had changed. They are now 17" 285's. and I haven't recalibrated the speedometer.

gitrdun · 03-28-2008, 06:54 AM

I have the LLY Duramax, fuel mileage when pulling 2980 about 11 to 12.2. Empty 16 to 20 depending on speed. Keep tach at 2000 and you will get best milage anything above will use more fuel. The LBZ will do better because of the 6 speed Allison.

racerjoe · 03-28-2008, 07:15 AM

Some friends of mine that own diesels have said the new "super low sulfur" diesel fuel has dragged down their mileage. Has anyone else seen this change?

richfaa · 03-28-2008, 07:39 AM

bkirk..The problem is that most folks will be less that truthful about their MPG and here you go posting real MPG. Folks on this forum are real good about actual numbers.

I have a 08 Ford 6. 4L and get way worse MPG than folks on other forums. ULSD got the school I drive for 2 mpg less fuel milage as proved my our fuel logs before and after.

rogue · 03-28-2008, 08:07 AM

I have the 2007 Classic, with LBZ engine. Have 13k on it. I get between 9-11.5 towing 2955RL, and 16-18 without. Live in Oregon and these mileages are from the recent trip through CA, AZ, MN, and Texas, with speeds between 60-65.

I hit one spot coming out of Carlsbad NM climbing a grade, with 30-35 mph head winds towing that took me down to 7.9mpg. On the other end, driving down from Corpus Christi to South Padre Island I had a tail wind and hit 13mpg. But these were not normal.

Snownyet · 03-28-2008, 01:16 PM

I noticed a mileage and power loss when we switched to ULSD, Mileage has since improved but Im not so sure about the power, Id like to toss a tank of off road fuel in it to compare. Ive got 20k miles on my 2006 LBZ 4x4 crew with 265/75 tires and I get 15-16 empty around town, 18-20 empty on the highway and a consistent 11 while towing at 65-68mpg. I know where mileage is concerned Id much rather tackle a hill than a headwind.

racerjoe · 03-28-2008, 01:48 PM

I purchase off road fuel for our farm equipment, and as far as I knew, it is the same fuel only dye is added to show it is un-taxed.

SlickWillie · 03-29-2008, 03:34 AM

Quote:

quote:Originally posted by racerjoe

I purchase off road fuel for our farm equipment, and as far as I knew, it is the same fuel only dye is added to show it is un-taxed.

If the following C & P is correct, off road may now be 500 ppm in sulfur content. Looks to change in 2010.

Under regulations previously adopted by EPA, the petroleum refining industry met a June 2006 deadline to comply with stringent limitations on the sulfur content of highway diesel fuel. By this date, most refiners had to meet a 15 parts per million (ppm) sulfur limit for at least 80% of their highway diesel fuel production, with a 500 ppm (low sulfur diesel or LSD) cap on the remaining 20%. Further in June 2007, refiners must meet a 500 ppm sulfur cap on all off-road diesel produced with a 2010 deadline for all highway and some off-road diesel to be at the 15 ppm ULSD level. (Locomotive and marine diesel would remain at the 500 ppm sulfur cap in 2010.) There are pump label requirements effective 6/1/06 (highway rule) and 6/1/07 (nonroad rule).

racerjoe · 03-29-2008, 04:05 AM

Good info. thanks

EagleRunner · 03-29-2008, 11:04 AM

Bkirk,
your mileage is about average and you still have some miles to put on before your engine is really broke in. I get about 15 to 16 city driving while empty during the winter and about 16 to 17 during the summer. When I attach either the boat or the 2955rl, doesn't matter which one, the mileage drops to around 11 to 12 and if doing a lot of climbing with that load, down to 10. On one empty long-haul distance run I managed to ring in around 22, but that was running highway speed on relatively flat ground on I90 through the Dakotas last summer. I also got 14 last fall while pulling the Monty heading down from Spokane to Portland on I84 and south on I5 on a trip to the Oregon coast. I have approximately 32000 miles on my 2005 2500HD crew cab 4x4 and some say I still have some miles to go before it is truly broken in.

I also found that having a cover over the bed really helps in milage when running empty. I installed a Fold-A-Cover last summer and that was a sound investment. Not only does it lock down and secure my cargo but it also prevents my tailgate from being stolen. I don't use a vented gate. When I detach the Monty, I cover the bed with the hitch in place.

Look forward to better mileage after your engine is broken in.

Happy Trails!

Tom

billhoover · 03-29-2008, 03:04 PM

I don't see any difference between LSD and ULSD. 9 to 11.5 towing 16 to 20 empty.

rames14 · 03-29-2008, 03:40 PM

Just traded in the 2004 D/A and was a consistent 20 mpg when traveling empty on the highway under 70 mph. Headwinds affected it as well as over 70 mph. I agree that larger tires require recalculating in the computer. Pi * Diameter = circumferance. Larger diameter, more distance per revolution. The winter blend will also decrease mileage a little. Anxious to see how the new 3500 will do. It's showing 14.2 for the first 150 miles. Started at 7.5 and kept climbing.

bkirk · 03-30-2008, 04:43 AM

Thanks for all of the input. I think I am going to have the computer recalibrated since going to bigger tires. I wondered about that, obviously beyond just the speed odometer. Thanks to all who responded.

skypilot · 03-30-2008, 06:48 AM

Not sure about other areas but our off-road diesel around here is all ULSD. Dealer up near Kerney Nebraska had a little LSD left about a month ago -- neighbor hauling trailers for manufacturer got some in his 2008 Chev -- was not a happy camper at all. Regardless, he just got back yesterday from another run and that dealer is now ULSD as well. Believe it will depend on how much they sell and where you are as to what you get but I'm not reading of a whole lot of places still having LSD available.

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