Windchill not affecting inanimate objects is a partial fact.
Moving air will allow heat transfer to occur faster living or not (thus convection ovens, your radiator fan, etc.); however, there are a few differences:
The human body is constantly warm, so [assuming alive, and well circulating] while you feel cold; once your tractor hits -10, -20, whatever, it's there and doesn't care wind or not. If it's running; wind does have the same effects, except it doesn't mind being only 90F [or whatever other low temp your body doesn't like], and wind doesn't penetrate steel and fiberglass like it does your clothes.
Also [again assuing alive and well circulating] you lose heat at a constant rate instead of more and more slowly as the temperature nears the enviromental temps.
The human body has a very narrow "operating temp."; so while you get cold, your tractor is fine until somthing contracts so much as to bind another part or your fuel gels, etc. Plenty of stories about the trucker from Texas [or wherever], fills up on #2 coming into SD on a cold day and doesn't make ND. Of course, going down the road has it's own windchill, the natural one won't always be directly additive; but the same effect would have occured in the parking lot, which has a slighter different issue with the fuel not traveling through the lines as fast..
Thus, facing the radiator away from the wind would be helpful overnight, but not for several days of consistantly low temps.
Clear as a SD blizzard?! /forums/images/graemlins/grin.gif