Quote:
Originally Posted by Sularus
a few hundred feet at a time adds up. I wouldn't do it, Automatic transmissions are too costly to replace and refurbish to risk it. There is no way to save that much money in P&G or engine off coasting to risk any damage to the tranny. Remember, in most areas a automatic transmission replacement will run over 3500 USD.
It is all done based on someone's personal desire for risk vs. reward. I know that a transmission requires the pump to help cool and lubricate a transmission, especially after it is warmed up. I have a automatic and I will throw it into N for my coasts.
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No, the "few hundred feet at a time" do not add up.
The entire argument pleading destruction of the transmission is based entirely on the fluid overheating, losing lubricity, and causing friction damage inside the transmission. The problem is that every time you start the engine, regardless of what gear the transmission is in, even neutral, the fluid gets exchanged at the clutches and all wear parts, which means that the heated fluid has a chance to cool and be circulated, mixing with the other fluid.
Another thing that most people don't realize is that once your torque converter locks up, the transmission is no longer pumping fluid (in most cases) to the cooler at all. It's circulating strictly within the transmission, which means that the parts in the transmission don't even seem to be capable of overheating a large volume of fluid, provided it's exchanged regularly. The overheating of transmission fluid normally occurs when the torque converter slips for an extended period, such as abnormally long take-offs, brake launches, and uphill where alot of torque is needed and the converter is operating at higher speeds.
The worst thing that can happen "a few hundred feet at a time", as you put it, is premature fluid change requirement from the fluid being heated excessively, which still isn't likely to happen in a few seconds of coasting with the engine off.
This argument reminds me of people who honestly believe that if you start an engine after the oil has been drained, that it's going to grenade instantly. In both cases, there comes a point where I just roll my eyes and stop debating the issue.
You can consider this that point.