Proper Gear for Towing up Hills

ZeeLet50 wrote:
If you encounter hills or deep descents,use your tow/haul mode button as it will keep the engine/trans in higher rev and proper gear longer. It will also prevent convertor lockup which of course will drop fuel mileage. Just got back from a trip and averaged 10.8mpg as expected.

Tow/haul on my F150 only UNlocks the converter when necessary to shift gears. Otherwise it's locked up which generates less heat and is better for the tranny.

When not in tow/haul there would be long uphill grades where the tranny wouldn't downshift, but the converter would unlock and the rpm's increase. Keeps the torque up, but, again, not good for the tranny when towing.

Like you say, tow/haul also changes the shift points so you'll be in lower gears more often. Haven't checked closely, but it doesn't affect my mileage too badly; getting 13mpgUS with trailer+gear of 5000#.

Towing any high walled RV is a lot of work for an engine because of the aerodynamic drag. What transmission and axle ratio do you have? 4-spd, use 3rd gear or overdrive off. 6-spd, use M5 or maybe M4 depending on axle ratio.

Let it rev on hills, 4000-5000rpm is fine for the truck.

I don't notice much difference when cruising using my tow/haul, but I notice a big difference when slowing down and stopping. Tow/haul uses the trans to slow down the truck instead of relying strictly on the brakes to do all the work.
BTW, this is with an '09 Chev 2500 gasser.

Use tow haul when towing.

Just got back today from a 3 hour trip through the Ozarks, which includes several inclines and descents. Put it in drive, with trailer mode on, and all was good. We averaged 10.5 mpg for our 6 hour round trip.

My Rockwood is 25 feet, and pulled flawlessly.

romore wrote:
The transmission will select the proper gear for the hill. If the engine starts to lug or the transmission starts to hunt, slow down and select the lower gear. You will quickly learn what works best for each situation.

+1

Let the transmission pick the gear and if needed use the lever to prevent hunting. 3000 to 4200 rpm is completely normal for extended periods.

Put it drive and since it's an automatic transmission it will shift to whatever gear it NEED to climb the hill.
Good luck / Skip

You'll learn in a trip or two. I keep mine in 3rd instead of drive, with tow haul on. It puts my engine at about 2400rpm at 60mph and that is just enough for me to carry the rolling hills without loosing speed. Any lower in rpm and I either loose ground or downshift, both of which I try to avoid.

Zeelet, can you explain the converter lockup and fuel mileage? I feel when it happens (seems to gain abou 200rpm) but I don't understand how it relates to efficiency? I thought it was saving me from having to downshift, which would be more costly.

If you encounter hills or deep descents,use your tow/haul mode button as it will keep the engine/trans in higher rev and proper gear longer. It will also prevent convertor lockup which of course will drop fuel mileage. Just got back from a trip and averaged 10.8mpg as expected.

Increase downward pressure to the pedal on the right relative to the steepness of the incline .