Quote:
Originally Posted by Geonerd
The transmission fluid pump is driven from the input shaft, and will obviously not be pumping if the engine is not running. That leaves 'splashing' or static immersion in fluid as the only source of lubrication. Will that be enough? Unless you're a transmission designer or accomplished mechanic, you have no way of knowing. I'd argue that unless the car has an unlimited speed/range towing rating, coasting with the engine off will be potentially damaging. Asking on a forum like this is not going to provide a correct answer; just because someone else has been coasting without immediately blowing up their transmission does not mean that their car, or yours, won't suffer some level of damage.
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Very well said. About 35 years ago I burned out the clutches in my A/T by coasting in neutral and shifting it back into drive at highway speeds. It was an expensive lesson I never forgot.
Being now older (and wiser?) I went to a transmission shop recently and asked them about neutral coasting and re-engagement into drive. They advised against it. The only method that is foolproof for coasting in neutral is to roll to a stop (or at least a virtual stop) meaning less than 10 MPH. When you shift back into drive it will go into first gear with no harm done.