Climbing in the Rockies

Just came back from Glacier and 3060 miles. I mainly left it in drive with tow mode and engine brake on while on interstate but on areas where we had done some driving I went to manual mode, served me well. We averaged 12.4 MPG with about 2300 miles pulling the trailer, towing speeds of 60-65 MPH.

The Duramax/Allison combination with engine brake worked very well and with some 40+MPH crosswinds the StabiliTrak also made an appearance a few times.

ghorn wrote:
Take your time and enjoy the view rather than be wide-eyed locked onto the centerline.

You can go downhill too slow a thousand times.
You can go downhill too fast only once.

I like your logic. Very true. There have been times I wanted the truck to go slower and the auto mode did not kick in and had to do it manually. If you have a GPS you can see how sharp any curves are on the way down or if the road is straight. Remember, you only get the fast lane once.

Take your time and enjoy the view rather than be wide-eyed locked onto the centerline.

You can go downhill too slow a thousand times.
You can go downhill too fast only once.

The whole point of an automatic transmission is so you can put it in manual mode and control the shifting.

Your GMC has the Allison transmission with automatic grade braking feature. Just put it in Drive and worry about steering.

Unless you know the road, let the truck do the thinking in tow/haul mode. If you know the road, use the manual setting, because you can think ahead, the truck cannot.

The only time I needed the manual mode was on the million dollar highway north of Durango. The trailer brake controller died, and left me without trailer brakes. I used the manual shifting, just like Dad taught me to drive a dump truck. The gears are for dropping, the brakes are for stopping.

Here is another plug for the Ford dealer in Steamboat Springs for getting an out of towner back on the road.

Toolguy5 wrote:
Thanks everyone.

I have been in the smokies and I have left it in drive with tow haul and exhaust brake on and it works great. But I know the Rockies are a lot different.

So I will trust my truck and leave it in drive/ tow haul and exhaust brake on.

That'll work as well as you pickin your own gear for the most part.
The one siituation where you'll want to use manual mode is say it's a little too steep for the exh brake to hold you at a certain speed but you don't want it downshifting yet another gear and screaming when you tap the brakes. If you choose to use the service brakes a bit more then you can hold a gear manually.
Idk if that even makes sense. Basically to keep it from hunting downshifts you'd rather not have.
Then again, I drive my newer trucks with manual mode autos in manual mode sometimes just for fun. Give ya something else to do with your right thumb! Lol

Toolguy5 wrote:
Have a question.
I have a 3500 GMC diesel. My question I when in the mountain areas should I leave it in drive and use the exhaust brake, or put it in manual and shift gears when climbing and descending.
Never been in the Rockies.

I have read all entries so far and they all make good sense, but you did not indicate the weight of the load. Remember, the heavier the tow vehicle the harder it will be to stop momentum. A truck will work much easier with a 10K trailer than a 21K 5er.

Thanks everyone.

I have been in the smokies and I have left it in drive with tow haul and exhaust brake on and it works great. But I know the Rockies are a lot different.

So I will trust my truck and leave it in drive/ tow haul and exhaust brake on.

TravisG wrote:

JAC1982 wrote:
Have never used the manual option on our F350, and most of the towing driving we do is up and down grades. Just tow/haul mode and let it do its thing. We drive primarily in CO and WY.

HEY!!! We're neighbors! On my 2015 2500 Ram I select tow/haul mode and let the truck do the thinking, bone stock truck. On my 02 2500 Dodge that is a 6 speed manual with a little more work done to it, it's a different story. I look like Daniel Boone in a canoe with all the rowing I do up and down the hills!:)

Hi neighbor!

And yup, with these new trucks there's no work involved whatsoever. So nice :)

JAC1982 wrote:
Have never used the manual option on our F350, and most of the towing driving we do is up and down grades. Just tow/haul mode and let it do its thing. We drive primarily in CO and WY.

HEY!!! We're neighbors! On my 2015 2500 Ram I select tow/haul mode and let the truck do the thinking, bone stock truck. On my 02 2500 Dodge that is a 6 speed manual with a little more work done to it, it's a different story. I look like Daniel Boone in a canoe with all the rowing I do up and down the hills!:)