Engine as brakes down a mountain

Yes
I live in the mountains and do it all the time.
No one has mentioned your engine RPM's though. It is very important to watch that they don't go too high.

With my truck, when they start to climb above 4000, I'll slow it down with the brakes

Jack L

I would say it's the transmission that really determines what gear to use. If you shifter has three positions D 2, 1 I would start at the top of the hill in second and see how it controls the speed.

Realistically though this isn't a you get one shot and your done situation. You're at the top of the hill so the brakes are fairly cool and they will stop you if you need them. The gears are used for the long descents to hold back the speed so you don't overwork the brakes. But honestly I'll bet that every Cruise America rental has had the brakes abused and no downshifting and the renters did just fine.

So start at the top of the hall and drop it down one gear and see what happens. If the speed climbs rapidly step on the brakes and bring it back down 5 - 10 mph under your desired speed and drop it another gear. You'll figure out which gear works best fairly quickly.

I live, drive, and tow in the Sierra. If you find yourself riding the brakes, you need to downshift. Typical 6% grade usually finds me at 50 mph in third gear with occasional braking similar to Dennis_M_M's technique.

So does the Ford in Tow Haul mode. Down shifts when you tap the brakes.

Downshift. I learned that from the guys that drive the passanger vans up and down Mt. Washington in New Hampshire. Each van makes several trips a day with 8 passengers (plus driver). When I asked how often they had to change brake pads the driver said every couple of years since they seldom use the brakes comming down the hill. Usually second gear unless someone ahead is really slow then first gear.

Use whatever gear keeps your speed where you don't really need to use the regular service brakes very much. Let the engine do most of the braking. It won't overheat like your service brakes will. Just don't let it rev past the redline on the tach.

My Allison transmission down-shifts automatically, when you hit the brakes going down-hill, or just slowing down. It's really a handy feature when you're towing a trailer in the mountains.

Mountain driving is very simple:

Pick the max speed you want on the way down;

start is a lower gear and let the speed build until you hit your max speed;

then brake FIRMLY to bring speed 10 MPH below your max;

Release the brakes and let them cool as speed builds again.

repeat as needed

DO NOT RIDE THE BRAKES, let them cool between applications.

Gearing down to use the engine as a brake and not use service brakes works very well.
Today, I went down a very long hill in first gear with many, many curves and 20-25 mph curve speed limit. In between the curves, I just drove the same speed all the way down. Worked to allow traffic behind me to pass.
Many variables as speed and the incline varies.
So, first gear maybe too, slow.
It is far better to start in too low of gear as you can shift up a gear as needed.
Go slow and experiment.
You will figure out pretty quick.
I slow the speed down and then downshift.
Pat

Absolutely use engine braking when needed. It won't ruin your engine and it will keep your brakes from overheating. Second gear or even first can be used if it's steep. As mentioned already, watch the rpm's to avoid redline.