Coolant Thermos Question

Lol, well, I suppose it depends on your definition of warm. Is warm "the same temperature as the coolant that went in", or "anything above ambient temperature"?

The thermos just allows the ICE to get up to temperature more rapidly after a cold start. There would be a slight decrease in emissions as presumably the catalytic converter would also warm up faster so it operates at peak efficiency.

Does it matter how long the coolant stays warm for? Obviously, the shorter the timeframe, the warmer the coolant will be and the more benefit you'll get from it.

Dave

 

Fact: Toyota says 72 hours, I believe the ambient temperature they cite is 20 degrees F.

Fact: Nothing magical happens at the 72 hour point. The coolant doesn't go from "Hot" to "Cold" at the stroke of midnight.

Fact: The coolant will begin to cool the moment you turn the car off, even in the Thermos, so a restart after two hours will result in more fuel being burned than a restart after one hour.

Bottom line, the stored coolant helps make restarts MORE efficient, not totally efficient. That benefit will continue with decreasing effectiveness until the coolant in the Thermos reaches ambient temperature, which is certainly longer than 72 hours.