Alex, I have never heard of manually shifting an automatic causing any problems and have had no problems with any of my vehicles doing this. I pretty much always manually gear down for going down hills, around corners and just slowing down in traffic. I think some people just get ideas or hear rumors and think it's fact.

 

The GM master technican who works on my 2003 says if you Drive the car in some sort of sensible manner, change the fluid at around every 80K miles, the wheels will fall off before the transmission goes bad. Says these transmissions are some of the best ever built by GM.

 

4l60 in my '02 Silverado Z71 has 164,000. Its done some heavy trailer hauling over hundreds of miles many times, been beat on when it was newer but for the most part, it runs right down the road. No fear of it leaving me stranded. Occasionally the computer will get confused and make a dodgy shift but all in all it still shifts good and still shifts hard on a WOT upshift. Now In a vette, the 4l60 has less than half the weight to push around so you should be good for a long time.

 

Probably nothing (no difference and probably no added wear).

However, the problem usually arises when people drive an auto and elect to shift "not like the computer would". Guess it depends on how/when you are overriding the program and electing to shift yourself.

No disrespect intended to opinions otherwise, but engine/automatic transmission = go, brakes = stop. You can slow/stop with the tranny, but it's no where near as efficient, not designed to do that and in the long run may shorten the life of the tranny. I guess you could upshift (WOT) manually if you wanted to, I dont, and Im not sure I could shift any faster or more opportunely then the auto does for me.

Just an opinion.

 

This is interesting due to the fact that my transmission went out in my C5 at 95,568k miles and just had a complete rebuilt done to the transmission and when I went to pick it up this week the vette tech said that I should drive in 3rd gear in town if driving under 50 mph and shift into (D) Drive over 50 mph and it would not warm the transmission any thoughts on this I have always driven the car in (D) drive.

 

I usually drive in 3 in town below 50 mph because the tranny bogs if I try to accelerate without a kickdown, and I've been told this causes a buildup of heat. In town summer driving in D might add some wear to the tranny, but someone with more tranny experience will have to chime in.

I've been manually shifting for a while, with no loss of function. (I'm at 85,000) I can say I tried manually shifting vs computer shifting on the strip, and the computer beat me every time. Manually dropping the gears for a pass is probably the most advantageous aspect, since the kickdown may only give you D to 3, wheras I can usually drop into 2 and gather more steam.

JMHO

 

This old habit of downshifting to slow your car down comes from the time (1930's) when your brakes were not good enough to stop or hold back your car. The corvette as well as any modern car doesn't need to use the transmission for stopping power. Downshifting to slow down will only increase the finite number of times the transmission shifts before it is worn out. This applies to stick or auto.
That is the reason a city driven car will get fewer miles on the transmission as opposed to a freeway driven car, fewer shifts. Clutches wear out.
And as most of us know, heat is the number one killer of automatic transmissions.
When I owned my transmission shop, pulling loaded stock trailers with a Ford F250 with an E4OD in 4th gear would kill the transmission below 75,000 miles. With no major towing most all tranny's would go 125,000 miles or more.
Another old habit not needed today is popping the auto into neutral when setting at a light. At idle the torque converter is not putting any pressure on the clutches, little heat is built up, and no wear is occuring . Just keep your foot off the throttle.
I did have customers who could break an anvil with a rubber hammer, and I'd see them once in a while. But normally, I never saw my customers but once, except for the cowboys, over the time I had my shop.