Originally Posted by teamben158
You use it in cold weather to keep your car warm.
Shut the car off and it keeps the heat circulating for 30 minutes (I think?) because it keeps the water pump running.
It's pretty damn awesome over the winter.
If I recall correctly, the function will work so long there is "heat" left in the cooling water. So when your engine is completely warm (operating temperature) the function will work longer than when you only just started the engine. You typically need 10 miles to reach full operating temperature. Note that while the water temperature may reach its operating temperature sooner, the oil is not yet at normal operating temperature.