[Paul L]

Can anyone tell me if leaving the gearshift in drive when stopped at lights, stuck in traffic, etc is "bad" for the transmission? Is it better to shift into neutral in these situations? ....or can shifting back and forth from drive to neutral all the time also be "bad" but maybe in a different way?

Any "expert" knowledge on this would be appreciated as it is the source of a running disagreement between me and a friend for a long time.

Best Regards,

Paul

 

[adam1991]

The automatic transmission is a fluid drive; there's no mechanical coupling between the engine and transmission.

It's designed to be in gear when the car is stopped. Why would you think otherwise?

Yes, it's worse--far worse--to shift it back and forth from neutral to D all the time.

So what's with thinking that an auto trans shouldn't be left in D when the car is stopped??

 

[Jerry O1]

There used to be a school of thought which said that being stopped in traffic on a hot day for a prolonged period of time was the biggest killer of automatic transmissions. The thinking is the same as that which says you should not let the transmission work as a "hillholder", e.g. to let the transmission keep the car from rolling backward on an incline, instead of keeping a foot on the brake pedal. I believe the thinking was/is that the prolonged slippage in the torque converter builds a lot of heat and can cook the fluid, causing a lot of varnish and, as a consequence, a partially or totally non-functional transmission. When the transmission is in neutral the chances of it staying cooler could make for a longer life. Many folks endure endless traffic jams in hot weather and it would be interesting to hear their experiences in this regard. That said, it seems to me that a shift to neutral, at least once in a while, might help more than it would hurt.

Jerry O.
2001 GG LX