Tow/haul mode with my 6 speed Yukon Denali

[Busterbrown]

I posted this over on Tahoe Yukon forum and thought about getting some input from GMT nation members.

First time towing with my 08 Yukon XL Denali with the 6 speed tranny (6L80) and 6.2L L92 engine. Since I'm relatively new to towing with this fullsize truck, I had a question regarding towing my travel trailer. I know the purpose of the tow/haul option on the gear selector. When active, it changes shift points, stays in a lower gear longer, and downshifts quicker when slowing down.

My concern is this. If i'm cruising at highway speeds (60 mph) and maintaining that speed without hills or strain on the drive train, does it do more harm than good to turn off tow/haul mode and let the tranny run in its highest gear? My trailer is about 6100 lbs. I did install a 2nd aux trans fluid cooler in parallel the the OEM and my temps never go past 180 degrees.

I'm trying to see if I can optimize fuel economy without much strain on the drivetrain, transmission and torque converter. Outside of the ideal conditions of constant hwy speed, flat terrain, and cooler temps, the tow/haul mode will be used.

 

[littleblazer]

The 4l80s behind the old 3500s don't have tow haul and after 17 years of towing form trailers (10k) they are still fine. The mode as I know it on the 07 sierra actually seems prevents full tcc lock up on the highway... so when we take the boat to Connecticut we don't use it. As long as you're not mashing the pedal I can't see it hurting anything, just watch the temps. I'd also be willing to bet economy improvement would be marginal. You can do the same thing with your right foot, I've never really used the option.

But you'll probably get some answer stating it's the best thing since sliced bread and should always be used because the engineers know best... it's just like torque management imo. It keeps you from hurting anything. Or I'm totally wrong.

 

[Mooseman]

Used to have it in my old '00 Jimmy and it just changed the shift points higher. TCC still worked IIRC. I would still put it in 3rd when hauling a heavy load.

Just go with what the owners manual says. Best thing to do is add an aux cooler.