When I was stationed in Germany with the Army in the 80's, we went to Graff during the winter for our gunnery exercise. It got so cold that the .50's would freeze solid and not operate if we used the standard lubricants. We had to bring them inside the vehicles, let them thaw, wipe off the lubricants and put on a thin coat of a special arctic lubricant. If I remember correctly, the temps were in the -40 F range.
I always wondered why the Germans had so much trouble with the cold on the Eastern front. It gets plenty cold in Germany, especially in the mountains, and half the German army was in Russia for 4 years in WW1. You’d think they would have an institutional memory.