Duramax question

[Rawn77]

I have a '15 Duramax towing a '15 Classic. Through the mountains of Vermont & New Hampshire, I enable T/H only while descending hills which works amazing with the exhaust brake to keep the set speed.
If I keep T/H always engaged; she'll have a tendency to stay in 5th gear longer than I'd like.

In the city, I always keep her in T/H.

[ghaynes755]

I do the same thing with Tow/Haul as Ron. On the highway exhaust brake is on and not in T/H. Actually seems to improve MPG since you are in 6th instead of 5th gear. In traffic, either on the highway or in town typically use T/H as you get better down shifting if you need to slow down.

[SilverSinbad]

I am considering the 2015 2500 Duramax, can anyone comment on MPG?
Thanks

[ghaynes755]

towing a 2015 Classic, 12.5-13.5 range. Around town 16. Highway no towing 22-24.

And regular and diesel are the same price at the pump here in Erie, CO. $2.49

[slowmover]

Originally Posted by ghaynes755

towing a 2015 Classic, 12.5-13.5 range. Around town 16. Highway no towing 22-24.

And regular and diesel are the same price at the pump here in Erie, CO. $2.49

40% deduction isn't bad. It's within the usual 30-40% range. Same speed towing and solo? Use cruise in both instances? 14-15 is possible if so, would be my guess.

[ghaynes755]

Tow at 65 and use cruise most of the time. Actually much better mileage than my previous 2014 5.3l Sierra.

[cwf]

Our 2012 hits around 12MPG towing... on nice and flat running around 55 indicated, but close to 57-58 actual. When climbing hills (small Texas type) I hit around 9MPG.

Towing a 34' and usually loaded with headwinds..

[DHart]

Another data point... but not towing, we've been averaging around 17.5 mpg with mixed around town and highway driving during the first 1300 miles driving a 2015 Sierra Denali HD Duramax/Allison. And we LOVE this truck! The engine is surprisingly quiet, surprisingly powerful (fast!) and the features/creature comforts are great.

[Rawn77]

Pulling my 2015 Classic I get 14-15, real city stop n go 14, highway 22-24.
The best thing is when going up hills on the highway, she almost never downshifts.
Love the exhaust brake. I only use tow-haul in the city; not on the highway.
Great truck!!

[TinShack]

Originally Posted by SilverSinbad

I am considering the 2015 2500 Duramax, can anyone comment on MPG?
Thanks

Driving my 2015 2500 Denali Duramax with camper shell mostly in and around the mountains of California according to the handy-dandy trip calculator:

Towing (8700lb 28ft with slideout)- 14 Hwy (60mph) and 12 mixed driving
Not Towing- 20 Hwy(70mph) and 14 mixed diving

Diesel is about 50 cents per gallon cheaper than regular in our part of California right now.

[DHart]

I've read some comments, here on the forum, to the effect that 3/4 ton trucks, due to the heavier suspension, are not great choices for pulling Airstreams. The implication being that the suspension of a 3/4 ton truck is "hard" on Airstreams.

We chose a 2015 Denali HD Duramax/Allison to tow a 2016 30' International Serenity.

We made this choice for the extra "grunt" when going up mountain passes, the extra (exhaust) braking when descending long grades, the cargo capacity for having a little bit of safety-margin with our cargo needs, and the great towing mirrors. (We also LOVE the truck.)

Does anyone here feel that this is "less than a good" pairing of truck & trailer?

We live in the west and in addition to plenty of relatively flat-towing, often cross through the Rocky Mountain, Sierra Nevada, and Pacific Coast mountain ranges.

[ROBERTSUNRUS]

Originally Posted by DHart

I've read some comments, here on the forum, to the effect that 3/4 ton trucks, due to the heavier suspension, are not great choices for pulling Airstreams. The implication being that the suspension of a 3/4 ton truck is "hard" on Airstreams.

We chose a 2015 Denali HD Duramax/Allison to tow a 2016 30' International Serenity.

We made this choice for the extra "grunt" when going up mountain passes, the extra (exhaust) braking when descending long grades, the cargo capacity for having some safety-margin our cargo needs, and the towing mirrors.

Does anyone here feel that this is "less than a good" pairing of truck & trailer?

We live in the west and in addition to plenty of relatively flat-towing, often cross through the Rocky Mountain, Sierra Nevada, and Pacific Coast mountain ranges.

Hi, for your size trailer your truck will be just right. With your trailer's tongue weight and a few things in the bed, it should ride nice.

[moosetags]

We have pulled our three Airstreams (a 23FB and two 25FBs) over 140,000 miles with two 3/4 ton Suburbans and a one ton pick-up. These are the vehicles that can do the job. They have never hurt any of our Airstreams.

Brian

[dznf0g]

Originally Posted by DHart

I've read some comments, here on the forum, to the effect that 3/4 ton trucks, due to the heavier suspension, are not great choices for pulling Airstreams. The implication being that the suspension of a 3/4 ton truck is "hard" on Airstreams.

We chose a 2015 Denali HD Duramax/Allison to tow a 2016 30' International Serenity.

We made this choice for the extra "grunt" when going up mountain passes, the extra (exhaust) braking when descending long grades, the cargo capacity for having a little bit of safety-margin with our cargo needs, and the great towing mirrors. (We also LOVE the truck.)

Does anyone here feel that this is "less than a good" pairing of truck & trailer?

We live in the west and in addition to plenty of relatively flat-towing, often cross through the Rocky Mountain, Sierra Nevada, and Pacific Coast mountain ranges.

No, at least not with the widebody larger ASes. I have towed with everything from (1500) Avalanche, Escalade, Yukon XL, Suburban as well as (2500) Sierra, Silverado. I am currently towing with a 1500 Sierra 6.2L 8 speed (non-max tow).

Mind you, I carry 1500 - 2000#(sometimes) of people and toys in the TV, and the 1500s are OK...not scary at all, but just OK. I always feel like they are just a bit below the task.

The 2500s feel just right. Very solid footing and handling and are not rough on the AS at all. I have not seen any towing related issues with the AS. When the AS had low miles I had one exterior rivet (on the back of the trailer) and one interior rivet (in the front) pop. But, I have the belief that that is normal on a new build, as there might be "build stressed" areas of the trailer, which, after settling and vibrating down the road, pop. After break in, I have seen no rivets pop in 4 years.

I have run EQ/1000# bars, Reese DC/800# bars and HAHA/1000# bars.

AS is a 30' Classic and weighs in at 8500 - 9000#. TW at 900 - 1050#. - depending on how loaded and what gear is loaded for that trip.

IMO, a 1500 is fine, generally, for <27'ers. Of course your personal loading needs would affect that opinion.

[Jack46]

An update. We've traveled about 7,000 miles to and from the west with another 3000 to go. After the transmission adjustment the truck has run and pulled flawlessly. Over all, we are currently experiencing about 13.5 mpg.

[cwf]

Kewl!

[TinShack]

Originally Posted by Jack46

An update. We've traveled about 7,000 miles to and from the west with another 3000 to go. After the transmission adjustment the truck has run and pulled flawlessly. Over all, we are currently experiencing about 13.5 mpg.

That's great! Are you using the Tow/Haul mode when towing after the adjustment?

[66Overlander]

It should be pointed out that on GM trucks, Tow/Haul does more than just adjust transmission shift patterns. Another impact that may be important to trailer towers is that it increases the generator/alternator output voltage so that the trailer Battery will charge. If Tow/Haul is not engaged, the truck may reduce generator/alternator output voltage down to as low as about 12.8V when it determines that the truck battery is fully charged. This is done to improve fuel economy, but it may not adequately charge the trailer battery if it needs charging. With Tow/Haul engaged, the generator/alternator output will stay around 14.5V so that the trailer battery can be charged.

[moosetags]

That's good info about the tow/haul. Thanks.

Brian

[callmedave]

Don't forget that while towing with Tow/Haul mode the transmission runs appreciably cooler - always a good thing!
With our Denali we can toggle through the vehicle's "systems" monitor to display the transmission temperature - the temp always jumps up when I disengage T/H mode.
Dave