O.K. Mike, as someone who has owned and towed Montanas with a 2002 (7.3), 2004 (6.0), 2008 (6.4), 2011 (6.7), and now 2015 (6.7) Fords, I can give you my experiences with the 2015-2016 F350s.
Tow Haul – Use it! It is the first thing I turn on after starting the truck with the trailer attached. The onboard computer (TCM) is a lot smarter and quicker responding to what is going on with the engine and drive train that anyone else’s seat –of-the-pants. It does two things (at least). It raises the shift points so the next up shift puts the RPMs in the sweet spot for towing a load. It also provides braking by developing back pressure via the turbo. This braking is most effective at higher RPMs (3000-3500). Do not be afraid when it does this. It is designed to work that way.
One way to invoke the braking is to press and release the brake pedal. This causes a downshift to the next lower gear (assuming it will not cause excessive RPMs – the TCM knows). The RPMs increase and with the throttle closed, the back pressure slows the vehicle. Keep pressing and releasing the brake pedal until the RPMs and back pressure are sufficient to hold the speed you desire. With the 2011 and the 2015 towing 16,500 lbs., I find 3rd gear will keep me in the 60 MPH range and 2nd gear holds me around 45 MPH. Depending on your gearing it the speed may differ for you.
One thing you will experience is after descending a hill w/Tow Haul and higher RPMs, is the application of throttle pressure to hold and increase speed causes the engine to increase RPMs before it up shifts. Rather than overspeed the engine (even though this is how it is designed to work), I prefer to turn off Tow Haul and then turn it on again. This results in an immediate up shift without increasing RPMs.
Manual Shift – Your Ford has the manual shift feature. You can select “M” with the gear shift and change gears using the “+” and “-“ buttons on the column. I don’t know anyone who uses this regularly. What I do use is the “+” and “-“ buttons to down shift to specific gears before Tow Haul does or when I am not using Tow Haul. This function also limits what gears are available to up shift to. Assume you are climbing a grade with various degrees of slope. 6th gear won’t pull the steeper portion, and the TCM down shifts the 5th. Then the slope lessens and the TCM up shifts back to 6th. Oops, here comes the slope again and it down shifts to 5th, then you pull back on the throttle and it up shifts. This hunting will continue all the way up the hill. You can lock out 6th gear by using the “+” and “-“ buttons. Hit the “-“ button and the number 6 disappears from the LCD display (no numbers in the LCD display?? – hit the “-“ button and they will appear). It is no longer available to up shift to and the transmission will stay in 5th regardless. Hit the “+” button to restore 6th gear to the display and allow up shifts to it. You can do this with all the gears. I often lock the tranny into 3rd coming down the Siskiyous.
Exhaust Brake – The 2015-2016s have an Exhaust Brake function. The button to turn it on is located on the lower right of the dash. What it actually does is not very well documented. The Ford manual basically says it helps slow the vehicle. Speculation is that it locks up the transmission and employs the Turbo in some manner. I can tell you it does provide additional braking power than just Tow Haul by itself. I use it when I am descending steep hills with the RV (think Siskiyous again) along with Tow Haul. I use it when not towing if driving in the mountains. Since it seems to disable the “glide” mode of the transmission (where you coast along with no engine drag) I assume it will lower your mileage if you leave it on all the time. I haven’t used it enough to say for sure.
Cruise Control – I use it on relatively flat roads as do many others. I do turn it off in the hills as maintaining a constant speed is contrary to how I like to drive hills and conflicts with Tow Haul in some cases.
Truck Apps – This is a selection in the LCD display panel (along with Gauges, Trip, Fuel, Settings, and Info) which contains the Trailer Mileage app Artimus Gorden referred to. The Ford will track the mileage your trailer has been towed. It senses when the 7 Pin plug has been connected (apparently the integrated brake controller is what triggers it) and records how many miles you have gone with the trailer attached. There is a default trailer bucket which you can rename to something meaningful. If you have multiple trailers you want to track, you can create buckets for them and name them. Then you have to manually switch the “Active” trailer to the non-default one you are towing. I only have one trailer to track and the renamed default works well for me.
Tail Gate – You didn’t ask about the tail gate but you should. The Ford tailgate, particularly those with the man-step and/or backup camera, is a valuable item. Low life’s know they can get $1,500 for one, no questions asked, at the local chop shop. Unlocked it only takes seconds to remove it. Even locked it can disappear in a minute. It costs around $5,500 to replace (ask me how I know). There are several tail gate locks available which will prevent the easy theft. I bought the Jimmy Jammer Gate Keeper (
http://www.jimmijammer.com/Product,%20GK.htm) to protect mine. Now there are a couple of competitors. This is cheap insurance against the tailgate walking way.
If you have any questions, let me know.