Oil Consumption of Super 6

Unknown

Hi Folks,
Has anyone any idea what the oil consumption should be for a 1921 Hudson Super 6 Phaeton, assuming it to be well sorted, or even when new?
I'm just doing a lot of road testing on mine and I suspect I may be loosing oil out of the back of the engine somewhere, although there is little static leakage and the exhaust I am told is reasonably smoke free.
If oil is escaping at the rear what are the most likely causes. Please don't tell me that the crank shaft has to come out!
Robert