Just curious if anyone else tows their fifth wheel or gooseneck in fifth gear instead of sixth? I have found that sixth seems to lug the engine a little more than I like in slower, <65 mph, areas. I have experimented with my Spartan gauge reader and engine seems to use more diesel (shown in liters/hr) in sixth at the slower speeds and EGTs are higher than when I kick it down to fifth. Trans temp stays the same either gear. Don't get me wrong, the truck will tow in sixth all day long. Just my observations at the difference. Fifth wheel is ~12000 pounds and gooseneck a little more FWIW.

 

I tow heavy a lot, up to 14K, and never tow in 5th, unless it's just because the transmission downshifts to there on a pull for a short time.

And I generally hold myself to around 65 towing on the interstate, slower than that on secondary roads.

 

I'm towing around 12,500. My towing mileage usually averages at 11.5 with freeway speeds at 65. It doesn't take much pedal to have trans kick down to 5th while in Tow/Haul mode. I haven't manually dropped down to 5th while on the flat but I will generally use use manual while towing depending on % of grade and if the road is too winding to where the trans is shifting up or down too frequently.

 

I tow 12K with my '12 and the only time I lock out 6th is if the transmission is doing a lot of shifting back and forth.. Just towed from Waco to Rockport and back with 12.7 going and 11.2 coming back against the north wind. Around here there isn't much use to lock out 6th get into a lot of hills then that's another story but I'm running 3:31's with 32.5" tires.. I also never tow over 65mph as that's all the trailer tires are rated for.

 

I tow heavy and leave it to the cruise control on the flats. Usually in 6th gear @ 65 mph.


Any real mountains and I switch to manual. Going up hill I give it all she has.


Down hill I use whatever gear will keep me safe.

 

I use M almost exclusively when towing, no matter what roads I'm on.

I use 5th when cruising between 60-65 for same reasons you do. It's just where the engine wants to be, 6th gear at 62mph is not the best. I don't know what it is but I can feel the engine not wanting to be in this situation.

On the interstate at 72mph I'm in 6th, which is happy, which is the same as 60mph in 5th. Occasionally on a long flat two lane at 60mph I will use 6th but it's definitely not the norm.

I like using M a lot. I do not like winding the motor out to and past 3000 rpm. There is just no reason for it. My shift points are generally around 2700. I try to accelerate slowly enough to get the torque converter to lock up early, then the hammer goes down.

 

There seems to be a few that use M when towing. In my case I use the +/- buttons to set the highest gear. Living in the NW there's hardly a trip that doesn't include going up and down some steep mountain passes. What would be the advantage of using manual?

Rob

 

I let the truck run in the gear it wants to unless in the hills, then I do it manually. It seems to know how it wants to run most of the time, so I let it.

 

Like many here I mostly let the tranny do its own thing. We tow a 5th at 12700# and I'm always under 65. On the flat I use cruise and my mpg is in the 13's pretty solid. I'll step in with the +/- button if the tranny starts hunting gears.

 

I just put it in drive along with Tow-Haul and Engine Brake engaged and let the computer to all the work.. I'm hauling up to 18k in a 13' tall tailer. You guys gotta remember that the torque peak of these engines is reached just over 1600 RPM so revving it out any higher than that simply does not make sense.

 

More info here;
6.7L Power Stroke Specs

 

Yup, forgot about tow-haul, nice feature.

 

Sure it makes sense. Just look at the chart you posted and you will see that you only have about 225HP at 1600 RPM. If you need more power you have to rev it up.

 

The Idea is to use the HP to get going and then use the torgue to keep it moving.

 

Torque does the work. Horsepower is the speed in which the work is done.