Tow Haul Mode

[grizz272]

I have a F350 4x4 long box diesel.  I always used tow haul when I towed our fifth wheel.   We have now downsized to a tow behind TT.  The friends we camp with have TT and they never use tow haul because they get worse mileage when they use tow haul.  One has a F150 v6 and the other has a Ram 1500 with hemi.  What is the story with tow haul mode  and travel trailers?   All 3 travel trailers are 19 ft and around 6500lbs.

[grizz272]

One of the guys had to replace the transmission on his F150 he blamed the mountains.   I bet he was not using tow haul while driving in the mountains.

[valhalla360]

That tells us nothing.  We don't know if he was using tow/haul or not,  we don't know what he was towing,  we don't know how bad the grades were,  we don't know if he maintained the truck,  etc....

[way2roll]

Tow/Haul mode is exactly what the name applies. It changes the shift patterns to allow for easier towing, both on the driver and the equipment. In most models it also allows for a type of engine braking for descents. I guess on the flats you could turn it off, but any time I towed our FW or when we had a gas MH and towed a car, I always used the tow/haul mode. That's what it was designed for, and I imagine there is a risk to prematurely aging or even damaging the engine or transmission if you towed without it. I don't see how a TT would be any different. It does use more fuel. How much is debatable. I have never purchased any RV with mileage as a consideration otherwise I'd have bought a condo and a prius. 

[CarnationSailor]

My 2015 diesel 2500HD Silverado locks out the highest (6th) gear when in tow/haul mode. I could get about 1 to 1.5 mpg more if I didn't use tow/haul, but I side with those of the opinion that it is easier on the transmission if I use tow/haul.

[Grit_dog]

No, it doesn’t lock out 6th gear. 

[valhalla360]

Interesting, our 2008 F250 with 5 speed is happy to go into 5th with tow/haul on so long as it's flat ground (climbing it will drop gears as needed). Doing a little search on the internet, it seems all over the place in terms if transmissions lock out the top gear in tow/haul.

[Grit_dog]

Have yet to see a tow/haul that locks out the top gear on any brand or configuration of domestic truck, light or heavy duty. 
I’ve owned, driven, or been assigned most every brand and model of new truck over the last 30 years.