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We've all been there, waiting on a train at a railroad crossing, or stuck in a traffic jam that doesn't appear to be going anywhere for awhile. Well transmissions are designed to my understanding for you to go, much more so then to stay the brakes at a stop. So during times of prolonged stopping, should you put your car in park to prevent transmission from overheating or is this really not necessary in modern cars?

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    I'm assuming this is referring to an automatic transmission. It would probably be a good idea to know the year and make of the car. Some newer automatics are not really automatics at all with the old-style torque converters, etc. Some of the new automatics are really dual clutch standards where the computer will actually put them into neutral when you are stepping on the brake.
    – mark b
    Jul 4, 2019 at 19:10
  • If you're stopped long enough to consider this, why is the vehicle idling in the first place? A modern car will run the AC without the engine running (or you can enjoy the breeze), and minutes of idling is a waste of gas IMO Jul 4, 2019 at 19:16
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    Well Brydon, you are not idling for the sake of idling, you are waiting for a train to pass or stuck in a traffic jam.
    – Travis
    Jul 4, 2019 at 19:30
  • I’m pretty sure there is no risk of overheating, but putting the transmission in neutral or park will decrease the load on the engine and therefore make it waste less fuel while stationary,
    – HandyHowie
    Jul 4, 2019 at 21:06
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    @Milwrdfan I'm not sure why I said that, I must have been naive at the time because that is incorrect. The blower fan will still run, and the compressor block will still remain cold for some time (moreso if recirc is used), but no, the compressor won't run. I'm sure there's some vehicles out there with an electric compressor, but I couldn't give an example off hand Nov 23, 2021 at 16:15

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The transmission will get hotter if it is working at maximum, such as towing a trailer uphill, that will be when the transmission cooling system will be needing to work at maximum and, if the cooling air flow is dirty or obstructed, when the problems will occur.

But using park or neutral will take the load off the drive train in the box and reduce the fuel consumption a small amount.

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    When the engine is running the torque converter is churning ,oil , therefore heating it. In neutral oil levels change and various clutches are engaged or released . so it tends to make less heat . But to significantly reduce transmission heat , turn off the engine. Mar 26, 2021 at 14:54
  • @blacksmith37 Not that there's airflow at idle, but does the transmission cooler (if equipped) still flow oil in neutral? It may actually be better to run the engine - you could be actively cooling the tranmission, if it is above normal operating temperature Nov 24, 2021 at 14:59
  • If you turn off the engine , the hot metal in the block and heads will put heat into the antifreeze for many minutes . So ,sort of a catch 22, not an obvious help to cooling to turn off the engine. partly depending on time. Nov 25, 2021 at 0:13

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