That's an interesting point, I tried to search but I couldn't find any examples. Can you really run a watercooled engine without coolant or a radiator in arctic (-40 to -50C ambient temperatures?). Its not like an air cooled engine designed for natural convection.

Seems like at the very least they could run the engine as long as possible until its about to overheat, then turn it off and it will very quickly return to operable temperatures in the very cold conditions. Certainly better than dying outside in Siberia!