Oil viscosity (weight) for model A

[40 Deluxe]

A question(s) for Mr. Kohnke: Assuming a stock 'A' engine with Babbitt bearings, how long after a cold start can it safely run without oil reaching the mains (or refilling the dipper tray)?
Now, say your A has sat in an unheated garage for a month. You go to start it tomorrow morning when it's 14 above. How long before oil reaches the mains and dipper tray?

I'm going to say a cold engine will run a lot longer (without any damage) before oil gets to the bearings than the average person would think. Or else no Model A would have made it past it's first winter!