Question: Towing with GM 8 speed

[fillwa]

For city driving I might use tow/haul mode. For hilly or windy back roads I use tow/haul mode. For highway I just drive normal. Always have the shifter in D. If the highway is mostly flat I use the cruise control and cancel it when it started down shifting down shifting.
2016 2500 LTZ with tow pkg and 6.0 gasser.
Never had a problem. I tow around 66mph on highway. No hurry, no worry.

[Leon]

Toe /haul mode is only necessary when your pulling max load or close to the maximum the truck can handle otherwise your just waisting fuel especially with a Duramax / Allision because it takes quite a load to get that truck to grunt .You can turn on tow/haul , also engine braking in a steep climb or steep decent on a mountain than turn it off when just cruising along.
Just select drive and go no worries

[bgelyhome]

I just put my GMC in Tow Mode and let it take care of the gear arrangement. That is what that function is designed to do.

[jimmoore13]

Shift manually and use your tachometer as your guide. On straight and level interstate at sea level, you may be able to just put it in drive and tow/haul mode and let it do its thing. But in the mountains, manual shifting can keep you at the torque/power peak for climbs, prevent transmission "hunting" every time you lift off a bit to round a turn during a long climb, a it will enable effective engine braking for long downhill runs.

[jimmoore13]

Originally Posted by Leon

Toe /haul mode is only necessary when your pulling max load or close to the maximum the truck can handle otherwise your just waisting fuel especially with a Duramax / Allision because it takes quite a load to get that truck to grunt .You can turn on tow/haul , also engine braking in a steep climb or steep decent on a mountain than turn it off when just cruising along.
Just select drive and go no worries

The OP is towing with a half-ton.

[Leon]

Yes it is designed for towing loads that are at the peak load capacity or hill climbing and it works well.
If you read the manual it sort of explains that .
In most cruising down a flat highway your engine isomer reving and gearing down to early is actually hurtful and burns too much fuel if you can set your cruise control and works ok out of tow/haul mode then it’s not pulling that hard .If you were pulling a real heavy load and really working the truck your cruise will shut down on it’s own most of the time

[Velz]

Originally Posted by DocBrown

I've had nothing but 4 speed automatics until now. I always towed in 3rd. What gear should I be using for the 8 speed? I'm assuming 7 but...

I have a 2018 8 speed 6.2L 1500 and tow a 24.5 Baja. I don't know about the 5.3 but I just put it in tow/haul and let the computer figure it out. No problem, that's what it's for.



On a flat stretch of hiway, I take it out of tow/haul for an improvement in fuel economy. I tow at 65, but will pass when necessary.

[LittleBill]

Originally Posted by newhampshirecampers

I have a 6 speed GMC 3/4 ton with tow package. Is possible to tow a 155th 000 lb wheel?

You don't indicate whether or not your 3/4 is diesel or not and whether you have a short bed (std) or long bed. I have a 2015 3/4 diesel short bed crew cab and pull a 16525 GVW 5th wheel and have not had any problem. Most trips I have been around 24,000 lbs CGVW It has plenty of power and I get about 9.5-10.5 MPG pulling it in tow/haul mode. It will pull at 70-75 mph if I would feel inclined to but I keep it down to 65-67 mph.

That being said, I am planning on getting a new 2021 1 ton dually in the near future. In fact there is one I think will fit my bill is in transit to a dealer about 20 miles from me. Looking at doing a Rocky Mountain trip either later this year or next and want the dual wheels for coming down the mountains. I'm also looking at adding disc brakes to my 5er before that trip too.

One thing you definitely need to get is a slider hitch if your TV is a short bed. I have a Demco Auto-slider and would recommend you take a serious look at one. If you don't get a slider you can very well damage your short bed truck along with your 5th wheel.

Good luck

[Hollander Mutthaulers]

My 16XRB is light but has a lot of wind resistance. I put my relatively big 5.3 in M5 and use T/H mode. It works very well and will usually allow me 70 mph at 2200 rpm through basically level areas like IL, IA, NE. There is no significant transmission shifting, trans temp stays well below 200, and it gets about 10mpg overall - 9-11 depending...

Lot of different variables with TV, RV, elevation, wind, grades. Seems everyone just needs to read up, try out, and do what feels right within the parameters of the mechanics involved.

[newhampshirecampers]

Originally Posted by LittleBill

You don't indicate whether or not your 3/4 is diesel or not and whether you have a short bed (std) or long bed. I have a 2015 3/4 diesel short bed crew cab and pull a 16525 GVW 5th wheel and have not had any problem. Most trips I have been around 24,000 lbs CGVW It has plenty of power and I get about 9.5-10.5 MPG pulling it in tow/haul mode. It will pull at 70-75 mph if I would feel inclined to but I keep it down to 65-67 mph.

That being said, I am planning on getting a new 2021 1 ton dually in the near future. In fact there is one I think will fit my bill is in transit to a dealer about 20 miles from me. Looking at doing a Rocky Mountain trip either later this year or next and want the dual wheels for coming down the mountains. I'm also looking at adding disc brakes to my 5er before that trip too.

One thing you definitely need to get is a slider hitch if your TV is a short bed. I have a Demco Auto-slider and would recommend you take a serious look at one. If you don't get a slider you can very well damage your short bed truck along with your 5th wheel.

Good luck

Mine is a gas 6.0. Thanks for the info.

[kblast523]

Originally Posted by Hollander Mutthaulers

My 16XRB is light but has a lot of wind resistance. I put my relatively big 5.3 in M5 and use T/H mode. It works very well and will usually allow me 70 mph at 2200 rpm through basically level areas like IL, IA, NE. There is no significant transmission shifting, trans temp stays well below 200, and it gets about 10mpg overall - 9-11 depending...

Lot of different variables with TV, RV, elevation, wind, grades. Seems everyone just needs to read up, try out, and do what feels right within the parameters of the mechanics involved.

To confirm the light weight/mileage:
2012 Jayflight SLX 185RB, behind a 2007 F-150 4.2L 5 speed: 11-12 mpg in spite of overload. Same trailer behind a Ford Flex 3.5L 10-11 mpg. Then behind a 2015 F-150 EB 2.7L 10-11 mpg.
2016 Salem 241QBXL behind 2016 F-150 EB 2.7L 10-11 mpg.
2018 Jayco Jayfeather 23 RL: behind 2016 F-150 EB 2.7L 10-11 mpg, behind a 2019 RAM 1500 5.7L 8-10 mpg, and behind 2018 Nissan Titan 5.6L 10-12 mpg.
The 2007 F-150 V-6 5 speed was 1,000 lbs over tow rating with the 185RB behind it.
The Ford Flex was 1,000 lbs under tow rating with the 185 RB behind it.
The F-150 2.7L had tow rating of 7,200 lbs, the 241 QBXL weighed 4,800 with load cap of 7,000. The Jayfeather 23RL weighs 4,720, load cap of 6,000.
The 2019 Ram 1500 had tow rating of 8,100 lbs.
The 2018 Titan has tow rating of 9,200 lbs, I also have pulled (not very far, 20 or so miles) a 2005 Layton Skyline 249H which weighs 6,850 unloaded. It was as well behaved as the much lighter 185RB.

Pro tip: The high wind resistance on any trailer is not created as much by the front, but by the HUGE hole is sucks in the wind...

[Icy]

I am a GM retired mechanic from Canada. I towed an Airstream for years and always found that if you keep your RPM within your engine torque range you will get your best MPG and good power. Eg. MAX torque between 1800 - 2500 RPM (NOT HORSE POWER - TORQUE). On your 6.2l 2500 RPM would be a good start to cruise at, what ever gear that would be. I always found best RPM range best fuel economy and best for your engine.

[kblast523]

Originally Posted by Icy

I am a GM retired mechanic from Canada. I towed an Airstream for years and always found that if you keep your RPM within your engine torque range you will get your best MPG and good power. Eg. MAX torque between 1800 - 2500 RPM (NOT HORSE POWER - TORQUE). On your 6.2l 2500 RPM would be a good start to cruise at, what ever gear that would be. I always found best RPM range best fuel economy and best for your engine.

The 2017-2019 Nissan 5.6L V-8 produces peak torque at 4,100 rpm, peak hp at 5,750 rpm. In tow-haul mode with cruise on the transmission will select gearing and run the engine somewhere around 4,000 rpm-and up. Fuel mileage drops like a rock to around 6.6-7.5 mpg. Using the right pedal and allowing the speed to drift three to five mph results in 10-11.5 mpg and engine only running 2,500 to 3,500 rpm (approx 350 ft lbs and 325 hp). I'll use the footfeed every day. Did you know Nissan uses variable valve lift as a throttle?

[Steve Hhll]

Depends on where you are, what you're towing, how much you're concerned about fuel economy, and how robust your transmission is. If you have a weak transmission downshift when it looks like you will need it or use tow/haul mode. The higher the gear the better your fuel economy.

[CAG]

Originally Posted by Leon

Toe /haul mode is only necessary when your pulling max load or close to the maximum the truck can handle otherwise your just waisting fuel especially with a Duramax / Allision because it takes quite a load to get that truck to grunt .You can turn on tow/haul , also engine braking in a steep climb or steep decent on a mountain than turn it off when just cruising along.
Just select drive and go no worries

You might want to read your manual. I think you will find that tow/haul is recommended at all speeds and all road conditions. Your gas mileage will not change but your performance will as it controls shift points as well as slowing. If you are towing 5K, yes maybe, but with my 5th wheel and two different Duramax trucks T/H was best and was the recommended condition. With the new, multi gear transmission T/H Keeps in the gears it should be rather than shifting from high “overdrive” gears even on the slightest hill.

And if you have a newer Durmax it is not “engine braking” it is “turbo breaking” the engine does no braking action in newer Duramax.