[grecy]

> This won't make any difference unless the thermostat is open

Actually, it makes a huge difference as it stops an enormous amount of very cold air going through/around the radiator onto the engine. Everyone up here does it, else cars would not be warm enough to run properly.

> Have you had your thermostat checked to make sure it's not stuck open?

Of course. Everything works great in summer when it's ~+25C

To give you a better understanding of how cold -50C actually is, I can drive for an hour, get out and put my hand directly on the exhaust manifold of my 4-cyl East-West engine (exhaust at front for cooling) and it's only just warm to the touch.

It's cold. Very cold.

[pdonis]

-50C

Ah, that explains it. :-) I used to do cold weather testing when I worked as an automotive engineer; the coldest we ever tested at was -30 C, and there were plenty of test vehicles that didn't fully warm up at that temperature.