Hi all,Took our first long trip with my newer tow vehicle. I went from a 2006 chevy Duramax to a 2012 6.0L gas with the 3.73 ratio. Now I fully understood there would be a difference due to it being a gas so that is not my issue here. But with a 5100lbs dry travel trailer(estimated 6500lbs max loaded) , I am no where near the limits of the truck. Well like I started off, too our first long trip, Central NY to Maine. Towing on the highway at 65mph it would not shift to 6th gear. Is this typical for this setup? I am strongly considering swapping the gear ratio to the 4.10 depending on the cost. In 5th gear I got like 8.5mpg which is what I expected, transmission was nice an cool typical temps in the 170-180 range, peaked at 186 climbing the Berkshires on the Mass turnpike, absolute max I seen was 196 when we slowed to a crawl in a traffic jam, but that was maybe 10 minutes.

I had an 09 like that. Just lock out 6th gear and drive.

Yep...normal and expected. Just consider 6th gear a grocery getter gear and forget about it while towing. A gear swap is an aweful expensive way to feel 6th gear the small percentage that you are towing.Thanks, Jeremiah

I have the same truch except a 13. Towing 8500 lbs its in 4th 30% of the time and 5th 70%. Never 6th even downhill.

The 6.0 barely has enough low end torque to hold 6th unloaded let alone towing 6500lbs. The slightest hill and it will downshift. Leave it in 5th when towing... THat motor needs to rev

2012 2500HD CC SB with 6.0L and 3.73 ratio | Good Sam Community

kw_00
Explorer
Aug 06, 2014
I use the toggle switch for selecting gears when I need to. So in locking out 6th I run 5th, but will run in 4th below 60mph. I love the 6 speeds, really a great match with the GM 6.0..
Frozen001
Explorer
Aug 05, 2014
Lantley wrote:
Funny this is not meant to be critical, what the OP describes and is happy with is exactly why I have a diesel. More shifting,more,revving and lower MPG's.

What I left out is the OP has lots more cash in his pocket after the sale which I totally understand. I also understand if you don't tow enough a diesel is just not money well spent.

Enjoy your new truck, it's nice to have options for every budget and camping style.

Yea I loved the diesel, but honestly the body on the 2006 was my problem, the drivers side under the carpet was total rust... traded it in before it got like that on the outside. The gas was a good deal, so considering I typically tow total about 3-4 weeks of the year and the cost different between diesel and gas in NY, I am actually saving money. Towing the same trailer with the diesel I was netting between 10-11mpg, so I honestly am not feeling the MPG loss.

The truck really does tow well, and honestly the ride is better than my 2006 was when towing. I do think it holds the gears a bit longer than needed ager cresting a hill sometimes, but then I tend to overthink things.
APT
Explorer
Aug 05, 2014
I tow 65-70mph usually and use Tow/haul and M5 to lock out 6th gear. At 65mpg, 6th gear would be about 1700rpm and not enough power. 5th gear is 2200rpm @ 65mph, which seems low too but it holds on flats and overpasses. My last 4-spd truck towed was happy in 3rd gear at 2800rpm. I get 7-9mpg at my speeds.
larry_barnhart
Explorer
Aug 05, 2014
Lantley wrote:
Funny this is not meant to be critical, what the OP describes and is happy with is exactly why I have a diesel. More shifting,more,revving and lower MPG's.

What I left out is the OP has lots more cash in his pocket after the sale which I totally understand. I also understand if you don't tow enough a diesel is just not money well spent.

Enjoy your new truck, it's nice to have options for every budget and camping style.

Nice response and very true

chevman
Lantley
Nomad
Aug 05, 2014
Funny this is not meant to be critical, what the OP describes and is happy with is exactly why I have a diesel. More shifting,more,revving and lower MPG's.

What I left out is the OP has lots more cash in his pocket after the sale which I totally understand. I also understand if you don't tow enough a diesel is just not money well spent.

Enjoy your new truck, it's nice to have options for every budget and camping style.
Mr_Beebo
Explorer
Aug 05, 2014
I have the 4.10 gears. 6th gear is not for towing. 8 1/2 mpg sounds about right. Honestly, the downshifts are smooth enough and the noise fairly subtle enough that I'm usually the only one who can notice it out of the four of us inside the cab.
Taco
Explorer
Aug 05, 2014
Mine will hold 6th gear for brief periods (a minute or two) on flat ground when the wind is right.

I just put it in D, push tow haul, set the cruise, and steer.
RCMAN46
Explorer
Aug 04, 2014
Not likely a 4.1 would allow you to hold 6th gear.

Now a 4.76 will allow you to hold 6th gear. But your overall gear ratio from engine to wheel would be the same as with the 3.73 in 5th gear. Nothing really gained except when unloaded your mileage will suffer at 80 mph as is the posted speed limit in much of Idaho and Utah now.

Gearing does not make more horsepower!
N-Trouble
Explorer
Aug 04, 2014
Your 2004 would have had the 4-speed and likely 4.10 gears. Apples to oranges...
Frozen001
Explorer
Aug 04, 2014
OK, sounds like all is good then.... The last 6.0 I has was a 2004 Reg cab/long box and only towed 3500 travel trailer, so I did not experience this. Pulled fine, although I thought the exhaust noise in the cab was somewhat loud under load, but that is just an annoyance.