Oil dilution, this a process where gasoline is added to the oil prior to the aircraft being shut down. There was no 10w-50 oil as we have today and simply adding a few squirts of gas prior to starting is not going to dilute 21 gal or more of 50 weight oil enough for a cold weather start. To be realistic you would have the ground crew start the engine long before the mission. If you wanted to do it correctly?
Researching this for the P-51 last year I found this under ""landing":
Page 27 of Army Manual AN 01-60JE-1 for the P-51D-5, stopping engine: "(2) If a cold weather start is anticipated, hold oil dilution switch, on pilot's switch panel, "ON" (2 minutes maximum)."