I have had autos for years and drive these mountains all the time and downshifting and using 2 is a part of the driving around here. I'm not talking abut down shifting at high speeds. That is asking for trouble! When I come to a steep decline I will slow down to less than 30 miles per hour before down shifting.Had an Auto 3/4 ton 4x4 Suburban for 13 years and drove it every day in these mountains and never had a tranny problem in all that time. My Tacoma is an 01 and never had a bit of trouble with the tranny.

 

yup this is true, but depending on where you are in the speed sometimes it can give a bit of a jerk to the vehicle, which can make things awkward on unfavourable roads.