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.

[Grit_dog]

Either use it or don’t, in your case, doesn’t matter. (Assuming you have a 6 or 10 speed F350)

Although even with a smaller load, T/H is nice if you’re up n down hills. 

[grizz272]

I did a test last weekend.   Heading to the camp ground tow haul on 11.6 mpg

Heading home tow haul off 10.4 mpg.   I could definitely hear and feel the transmission shifting a lot more.

[4x4ord]

What is the elevation of home vs the campground? Did you have more wind one way vs the other? I doubt Tow/Haul has anything to do with your fuel economy while towing. Tow/Haul on might adversely affect fuel economy in a non towing trip.

[way2roll]

So many factors come into play with MPG which is why most RVers never even bother. Terrain, weight, wind, traffic, speed, etc. Some fella at a gas station once asked me what kind of mileage I got on my class A. I said; it gets great mileage for an apartment. 

[valhalla360]

We've been tracking our travels with a spreadsheet that goes back to 2007. It includes, miles, travel hours and MPG for the day. It then pulls the data over and runs a long term average. I also make notes on driving condition as a strong head/tail wind,  was the drive hill with a lot of elevation gain/loss...these can have a significant impact on MPG (I've had it vary from 7.5mpg up to 16.8mpg).

For planning a long trip, I generally assume a bit less than the long term average. This gets used for general budgeting purposes.

For daily driving, I can get a pretty good idea of impacts on range based on the wind forecast and how hilly the route is. This is useful to determine if I need to fill up before we hook up. 

[ford_truck_guy]

This SOUNDS way too much like work ! ! ! Get in and rock and roll..... I know my truck, I know when the 48 gallons is getting low, and if traveling to parts unknown, I usually scope things out ahead of time on goggle maps around the mileage I usually need to refuel . . . 

[StirCrazy]

I wouldn't say RVers never bother, I know very few that don't track their milage.  for me I realize it is going to varry but not by much it is in a general range and if it goes out of that range for no aparent reason I know to start looking for somthing wrong like a wheel berring or what not.  plus I am always looking for ways to improve milage.  

[way2roll]

Good point. I don't track mileage in my RV or any car for that matter or chase price at the pump. I am going to need fuel either way and I know my vehicles well and have enough warnings bells and alerts on them to tell me if there's an issue. Your mileage may vary - pardon the pun. 

My overarching point was, I doubt Tow haul mode affects mileage much, but rather the other 100 other variables that can impact RV MPG. The only way to really know is to replicate the identical conditions and perform the test over and over. Hardly worth the effort. 

[4x4ord]

Using Tow/Haul is not going to affect fuel economy while towing and you are definitely not going to go wrong using it for all your towing. However, with a new F350 diesel towing a lighter tag trailer, something under 8k lbs, tow haul is hardly needed. If you find it more comfortable to tow light trailers set to "normal" I'd recommend using "normal" for towing.  Activating the Exhaust brake affects the shift points to some degree as well. Sometimes with a light trailers I'll use "normal" and no exhaust brake, sometimes "normal" plus EB. With a heavy trailer I usually use Tow/Haul with the EB set to "auto". If just driving on flat ground at slow speeds I will sometimes set the truck to normal no EB even with a moderately heavy trailer, (I consider my fiver a moderately heavy trailer at about 16000 lbs). 

[ford_truck_guy]

I ALWAYS use tow/haul with my 2020 F-350. when towing... That's what it is for, hence the name......

[QCMan]

Maybe it was what he was pulling that did it.

[StirCrazy]

in my f350 towhaul mode changrs your shift algarithims so when accellerating it lets you go a little higher in the rpm before shifting to the next gear, it also holds the gear a little longer before downshifting.  I tow a 13000lbs 5th wheel the only time I use it is on the bigger passes in the mountians and then only rarely.  

[Krusty]

I believe it increases line pressure which will help your transmission live longer. Especially if it is shifting a lot.

[valhalla360]

City driving there might be a small difference in mpg as it holds lower gears longer to improve performance. Once on the freeway and up to speed and locked into top gear,  it won't make any difference. I typically avoid city driving and have never noticed a difference in mpg. 

Where it really makes a difference is in the mountains.  Avoids hunting for gears which can be hard on the transmission and will help downshifting on downhills for a more comfortable and safer drive.  You could leave it off and manually force shifts but why?