Tow haul question

I always run T/H when towing or hauling. Sometimes even when not. If I need to slow down from highway speed at an exit ramp or something I'll turn it on even when empty.
I can't imagine it would effect MPG very much. Even if it does, I'll take happy engine, long transmission life, less brake maintenance, and an easier driving experience over a tiny, tiny MPG difference.

Pretend it's stil one of your handshakers with one less OD gear. Whatever keeps the trans in the right gear to keep the engine in the right range is the right choice.
I also run T/H even empty sometimes. Especially in the hills.

Diesels don't work like gas. A lugging diesel in 6th at 1,500 RPMs uses more fuel and it runs hotter than in 5th at 2,000 RPMs. I have a tune where it won't shift to 6th until it's over 68 MPH and if I'm driving through country with small ups and downs like Montana and Wyoming, I lock out 6th. Since I've done that, I've gotten noticeably better fuel mileage then just leaving it in the gear the computer wants it in.

Bet the mfg. has something about 'Tow/Haul' in owners manual....what, when, how, etc.


I always use it when towing or hauling

Some times I use it when NOT towing/hauling.

Another perspective: when I drive the C's and Class A gassers tow-haul is pretty much mandatory otherwise the acceleration is terrible. And the rigs are empty.

Embrace tow/haul. Don't forget or fear it.

I use Tow/Haul any time the trailer is attached. As stated above exhaust break works better.

Tow haul for me too....whenever I am towing. It changes the shift point. This helps the tranny run cooler and it activates "grade braking."

MPG...No such discussion when towing a 10K+ trailer in the mountains or anywhere else for that matter.

I forget to turn it on half the time because the stupid thing defaults off even with a trailer attached (unlike the EB). But yeah when I remember I always run it towing. It does get a little overly aggressive with the downshifting sometimes, especially on curvy roads where you will speed up and slow down over and over, but for the most part on all the time is fine.

I use the tow/haul all the time, towing or not. The reason that I do is that tow/haul allows the exhaust brake to be more aggressive. The truck will downshift more in tow/haul and allow the exhaust brake to continue down to about 20 mph or so. I find that I rarely have to use my service brakes, even around town.

Its personal preference, but I don't find that my fuel mileage suffers as a result.