I live on a very steep twisty mountain road. There's some Christmas tree farms on the road. Each fall when tree season starts you can tell because of the smell of burning brakes. Every few years a large truck loses its brakes on the road and crashes. You have to go down this road in a lower gear than "D" or you will burn up your brakes. And you need to not drag the brakes all the way or they will be smoking at the bottom of the road.
I've downshifted for steep downhills on every vehicle I have owned since I started driving in the '70s. Even before I moved to my current place a lot of those miles were in mountains as I worked for the USFS for a while and spent a lot of time in the mountains. I've yet to damage a transmission or engine from downshifting for downhills.
I have monitored trans temps in a number of vehicles including my GX. Downshifting on downhills does not raise transmission temps significantly. It's going up the hill that heats up the transmission.
I've downshifted for steep downhills on every vehicle I have owned since I started driving in the '70s. Even before I moved to my current place a lot of those miles were in mountains as I worked for the USFS for a while and spent a lot of time in the mountains. I've yet to damage a transmission or engine from downshifting for downhills.
I have monitored trans temps in a number of vehicles including my GX. Downshifting on downhills does not raise transmission temps significantly. It's going up the hill that heats up the transmission.