The old days, before electric heaters were commonplace and other forms of pre-heat were available, that is how the pilots were able to fly after a cold night (Alaska cold...-40f or worse). The pilots would carry an empty jerry-can with them and when done for the night would drain the oil. Pilot places all oil on wood stove in cabin where pilot sleeps. Stove keep oil toasty. In morning, pilot put hot oil right into cold oil pan and fire 'er up. It is still a very effective, if not rudimentary way to deal with super cold temps away from power sources or other forms of pre-heat.
Actually, this is not exactly the whole story. In fact, in the old days, pilots would drain the oil out of their engines, and park it near the wood stoves in the road houses. In the morning, however, they would then apply a large engine cover to the engine that draped all the way to the ground, light a fire pot (like a blow torch) put it under that engine cover. Once the engine was warm, the pilot then placed the warm oil into the oil tank.
Bear in mind that in the old days, most of these aircraft were equipped with radial engines. In these aircraft the oil resides in a separate oil tank, which is not close to the engine in many cases. So, just dumping warm oil into the oil tank does nothing to preheat the engine. And, since the oil tank is not located near the engine, it's impossible to heat that with an external heat source. Hence the pre heat of the engine AND the necessity to keep the oil warm all night, then dump it into a cold oil tank in the AM, once the engine was warm.
It was quite a process.
With opposed cylinder engines, just heating the oil isn't going to pre heat the critical parts of that engine prior to a cold start, unless you dump HOT oil into the engine, replace the engine cover, and let the thing sit for half an hour or so. Much better to simply pre-heat the engine, with the oil in the sump.
MTV
