Tow/haul mode with my 6 speed Yukon Denali

[busterbrown]

I'm relatively new to towing with my 2008 Yukon XL Denali and 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.

 

[drakon543]

There is no harm not using tow haul mode if you notice the truck isnt struggling even if your going up a hill. When you notice the truck is struggling to hold your speed is when you should use it. If your concerned you can also have an auxiliary pod mounted with a trans temp gauge. That way you can monitor the trans better and the aux cooler is always a good bet.

 

[Jonah52]

^has a trans gauge stock

I wouldn't worry about it once you're cruising. Getting up to speed is when you will need it. Won't hurt anything.

 

[drakon543]

^thx for the info i wasnt aware they did. Thats a nice factory feature i wish they had started doing that sooner.

 

[busterbrown]

Thanks for the info. Yeah, I think all of the GMT9XX's have the stock transmission temp gauge in the DIC. It's definitely a nice feature. As far as the tow/haul option, I'll assume best practice and use it when the truck demands it; but when cruising at hwy speeds, I'll turn it off and try and optimize fuel efficiency. The 6.2L with 6 speed trans pulls so much better than the previous generation with the 4 speed tranny.

 

[Jonah52]

My 07 has it and so does my 05. Just scroll through your gauges

 

[Jonah52]

Also remember debali has 6.2, 6 speed and a trans cooler. (Not sure about other platforms). Pair that with the autoride it is almost an sub equivalent of a heavy half ton (ish).

 

[STORMIN08]

Does your not shift into 6th in tow/haul...
I am certain mine does, and at that point, the rpms are only a couple hundred higher. I use it for increased line pressure for od clutch holding power.

 

[adventurenali92]

^thx for the info i wasnt aware they did. Thats a nice factory feature i wish they had started doing that sooner.

My 2006 Denali XL has a trans temp gauge to the left of my rpms. I keep a constant eye on my trans temp pretty much whenever im driving. Even on flat roads and just normal driving. But that's because I just had to have my trans rebuilt @ just over 83,000 miles. Not happy with that fact. But oh well. The trans temp,is a nice feature to have. I'm planning on adding a second trans cooler soon. So hopefully that will help keep the new trans cooler and more well maintained.

 

[busterbrown]

I'm planning on adding a second trans cooler soon. So hopefully that will help keep the new trans cooler anymore,well maintained.

I did this late last year in anticipation of towing my current trailer. The 2nd aux cooler is in line with the factory cooler. So far, temps have not exceeded 180 degrees. Definitely good practice.