That was exactly my concern regarding using a 0w oil. It may not provide a full wedge for the crank and the rods when its up to temperature. Personally, the 5w would be as light as I would go.
Alternatively, I'd suggest a crankcase heater if runs are planned and you can warm things up before starting the unit.
Nice Lister Petter chart!
By the numbers, there isn't a huge difference in viscosity between 0Wand 5W, but I do think staying as high as possible consistent with starting might be prudent because as
@Light in the Dark points out these aren't exactly tight tolerance engines, for better and worse. I also wonder to what extent some judicious vent blocking might be in order, depending on how cold it is.
FWIW: Eberspächer makes a variety of diesel fired air, coolant, and oil heaters, and there is (was?) a winterizationkit for the 803;
Anyone out there know where I can get winterization kits for an 802A & 803A? NSN 6115-01-476-8973 NSN 6115-01-477-0564 respectively. Anybody have any positive/negative experience with these?
www.steelsoldiers.com
All the best,
2Pbfeet