Piston engines on large aircraft also used fuel dilution of the oil where petrol was used to thin it out, the fuel boiling off as it warmed up, also they had what was called a hot pot in the oil tank, this was like a cylindrical colander and the return warm oil would enter one end and the engine supply left the other end, this enabled a portion of the oil to heat up quickly and supply the engine, as it warmed up the heat would radiate out into the tank and the rest of the oil would then flow through the holes of the colander and be available to the engine.
As for jets, I did an engine change outside on the pan in Gander Newfoundland at -15, it dropped to well below that at night, bottle water in the galley had all blown and the caps were frozen on stalks of water as it pushed out of the bottles. We had to leave all the connections slightly loose as in those temps it was easy to break something, then once it was running and got some heat through it we went round and tightened up all of the connections. We then pressurised the cabin with the door partially cracked open to get some heat through the cabin. The aircraft had been sitting outside for four days like that. We then flew back in it that day. Ohh and yes it was cold.