My son like to shift to to lower gears on his auto tran car when he comes to a stop. Can this damage the tran?

If he downshifts too soon, then you risk damage to the tranny and engine. Downshifting on an automatic is unnecessary.

it will take many thousands of miles of downshifting to cause major harm AS LONG AS HE DOES NOT DO IT TOO SOON. he is at more risk of blowing the engine than hurtin the trans. downshift too soon and the car will slow but engine will speed up. trannys are very tough. i don't think I've ever had a car or truck that i didn't downshift and they were all autos.

Yes - it can cause damage. I had a friend who ruined his tranny doing just that. An automatic is not meant to be shifted like a manual. There is danger of overrevving if he does it too soon which will harm the engine itself also.

bad bad bad idea.

Yes, and no.

It doesn't damage anything if he does it right.

While moving, he downshifts. If he lets out too quickly on the clutch, and you feel a crunch in the gear box and the car jerks, that's hard on the clutch.

However, if he eases out on the clutch to where it's smooth, it won't damage.

automatic trannys contain clutch surfaces not gears if you are aggressively down shifting ahead of the auto function you are causing premature wear on those bands.

unless he's got a truck and is downshifting with a trailer, its not necessary, every time you shift like that you are engaging/disengaging solenoids that causes minor wear and tear over time. tell him to just use the brake. going down a long mountain hill, he can put it in non-overdrive to slow his descent and prevent the brakes from over heating.

Yes. It puts additional load on the internal clutches. It 's also cheaper to repair brakes then a transmission.

Engine braking causes unnecessary wear on the tranny. It he wants a manual transmission, he should by a car with just that.

Eventually., unless the transmission was disigned for it - as in Porsche, Mercedes and other high end sports cars.

Only tools downshift with an automatic.