I remember a winter in the early 1960s that it was -30. The oil in my carwas so thick it was like paste. Had to put heat lights under the oil pan for a few hours to get the engine to turn over. Had to work that nite on the RR and had my face mask freeze from my breathing. That was while riding across the OHIO River on the 1st car to make sure no one was crossing the tracks in front of us going down hill in WVa. That was the coldest I have ever been. Just couldn't tell one of my brakeman to do it.