Active transmission warm-up is a system using waste heat from the vehicle for targeted warm up of the transmission. This reduces friction losses and enables a faster transition from cold operation to warm operation, thereby decreasing CO2 emissions, and increasing fuel economy.

Check the fluid. Dip the tip of your index finger into the fluid on the dipstick and rub the fluid between your finger and the tip of your thumb. The transmission fluid on the dipstick should be pinkish and almost clear. If it looks or smells burnt or has particles in it, have a mechanic drain and change the fluid.

Pull out the dipstick, wipe it clean, replace it slowly, and then pull it back out. Check the fluid level—how high the fluid comes up on the dipstick—against the “full” and “low” or “fill” marks on the dipstick. The color of transmission fluid can tell you a lot about the health of your car’s transmission.

There really isn’t a reason to warm it up, unless you are in extreme sub-zero temps. Letting the engine idle for a couple minutes should do the trick (that is even a hot debate). If you are experiencing trouble shifting when the trans is cold, it could be an indication of upcoming issues, so get it checked out.

The ideal temperature for it is 175 degrees, plus or minus 25 degrees, and when the transmission gets below zero degrees, it gets too thick. The fluid can also fail to lubricate parts when it is too cold, wearing parts down unnecessarily.

Yes, Park and Neutral (at a stop) are identical, both hydraulically and mechanically. So your trans will not warm up any faster in Neutral than it would in Park. If you actually want to reduce warmup time, you’ll need to put the trans in gear (Drive or Reverse).