I know its not all that relevant on this thread...but for what it is worth here is what we do with the PBY.
Each engine oil tank holds 55 imperial gallons of oil. 100 weight in winter and 120 weight in summer. ( That is 990 pounds total for the oil. )
We cannot use more than high idle RPM until oil temp shows 40 degrees C.
We must pre heat if the ambient temperature is plus 2 degrees C or lower.
Note:
There is an oil thremostat that ensures no oil will be taken from the oil tank until the temp of the engine oil reaches the proper temp....otherwise it would take forever to heat all the oil.
Chuck