i would only manual downshift an auto if you have too ie: going into a highway off ramp too fast, go fast around a hard corner, or pass someone on the highway. using it too much i'm pretty sure will mess stuff up. i think that's why my tranny started slipping 3rd-4th.

if you read in the owners manual it says you have to be below 60 or so to drop into 2nd. you sure as hell can't go 70 in 2nd gear so downshifting to 2nd at 70 will not be good. from my experience it will downshift,but slam into the rev limiter. i've downshifted to 3rd from 4th at 90 or so and it banged the rev limiter.