Under those conditions, the engine will reach optimal operating temperature in as few as 3--5 minutes, as opposed to running 7--10 minutes with improper (cold) engine clearances at idle.

Don't engines have thermostats to deliberately restrict the coolant flow, so that they warm up quickly at idle, whether you're driving the engine hard or not?

That was a rhetorical question, of course I know they exist, I had to replace one of those buggers myself. The question is whether or not they actually still do the job properly in subzero weather.


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Tony Fabris