I use manual mode exclusively when I'm towing heavy. As long as the road speed doesn't drop with cruise control on, I don't downshift on a hill. If the mph starts dropping, I'll downshift a gear. The transmission downshifts much earlier than the engine requires if you leave it in auto. I've pulled many hills in 4th or 5th gear while holding my desired speed, that the transmission would have downshifted to 2nd or 3rd if I'd have just mindlessly left it in drive (auto). These 6.2's have more bottom end torque than the transmission shift points give it credit for. Just "locking out gears" does not stop the trans from downshifting. Unless I'm on table-flat ground, I'm usually pulling in 5th (manual), and seldom if ever use 6th. There's just not that much flat ground where I'm pulling. Normally down to 4th is as low as I have to go, with some really steep grades I'll see 3rd. But I'm not hauling @zz when I'm pulling either. 70 mph is as fast as I'll pull, and that's on interstates. Rest of the time I'm pulling at 65 mph. Like a sane person. All this is manual shifting. The "computer" shifting is for the birds. The engine makes power down there, may as well use it too.

I recommend you try manual mode for yourself. You may be surprised on what a difference it makes. My truck drives like a totally different truck when pulling in manual. From reading some of the threads on these forums, I'd swear my truck was made of magic. Or some limited edition super-speed experimental truck. Just give the manual mode a fair try, and you'll likely never go back.

 

I use TH and just lock out 6th (or 5th) if the shifting is too frequent. Given what ford390gashog said regarding the TC lock-up, I'd rather the trans do it's thing and I'll just manage what little it left. If I see a hill upcoming (and you should if you're paying attention), I'll downshift by locking out another gear and preemptively compelling the trans to shift so that it's in the powerband sweet spot prior to the loading increase of the hill. Or, IOW, I pre-plan my shifts a few seconds in advance, and then I don't lose any speed. The CC keeps the vehicle speed where desired and I just keep the engine spinning in a decent range (2000 - 4000 rpm depending upon load).

 

I bought my f350 a little over a month ago, coming from a 2016 f150 5.0. Our trailer is roughly 7000#. We live in Saint Louis, MO and travel down to NW Arkansas about once a month through the ozark mountains, about a 300 mile round trip. On the way down I used TH mode with 6th locked out and on the way back I used manual mode. The computer in auto TH mode does shift a lot earlier than it needs too. In manual mode I could often hold a higher gear and still make it up the hill at a lower rpm. However, I did not see a noticeable difference in mpg in manual mode vs auto TH, even though in auto it was revving a lot higher much more often. It was also much easier to haul with the higher revs as I didn't have to floor the gas pedal. My best advice would be to user auto TH mode and when you see a hill coming up just give it some gas.

Either way the f350 is a HUGE improvement from our f150. I put almost 30000 miles of towing on the f150 all across the country including the mountains out west. It did the job, but the 350 is much much more stable. Plus the gas mileage towing is about the same. Looking forward to our first long trip with the 350.

 

 

Makes perfect sense, and I totally agree.