I went through my manual but could not find the answer. I have the 6 spd transmission with the tow/haul button. My trailer is a 27'. Is it safe to leave the shifter in D with the tow/haul activated or should I leave it in 3?

 

Use D with the tow/haul feature activated.

 

+1

towing in any other way would not give you the best performance.

 

+2

Which should put you in 4th with a locking torque converter.

 

In Tow/Haul mode towing my 24' 5,000# travel trailer, my tranny cruises in 6th on the flats at 65mph (about 1,850 rpm).

I've got the max tow package with the 3.73 rear.

 

Hmm interesting. Must be some intelligent system. I would like to see it work on an Edge Evolution. How do you know your in 6th?

 

yup I'm it top gear at hwy speeds ... how do i know ? rpms are almost the same as without .. the tow haul feature is far more advanced then previous OD lockout buttons

I tow in Drive with the tow haul features.. I've towed my trailer every other weekend since I got my truck I can tell right away if I forgot to turn the tow/haul on . The "engine brake" is really nice although the a time or two it's been annoying kicking in going down a hill where I didn't want it too..

BTW my trailer is 5500lbs

 

As a former Rocky Mountain driver - When in doubt, keep it out of Over Drive, and take it easy. No reason to hurt your horse.
Let the truck use its' gears going uphill and watch your temps. It aint' a race to the top, so there is no need to use the whip.
On the downhills - shift to a lower gear to let the engine do the braking to keep your speeds under control (I've driven down Pike's Peak with an autotrans having only needed to touch my brakes twice the whole way). Compression Braking is a good thing. Be in control BEFORE you crest the hill and start down - otherwise it may be too late.

 

I agree with you but this is a six speed tranny we're talking about not a 4 speed or a manual. Your options are 123D. So if you pick 3 you miss out on 4th and two overdrives. Kind of hard to maintain highway speeds or get any mpgs in 3rd gear. Good general advice just not too practical for this advanced six speed. Tow/Haul in drive is the only choice.