Duncan, I'm sure you're right regarding siphoning effect when the oil flow is continuous, for example with a force feed system as in a car. But a drip feed won't provide enough oil to maintain a continuous flow. Once it stops, if my theory is correct, it won't restart when the engine is running.

David, I suppose the hydrodynamic theory could be checked on a model by experiment. Remove the connecting rod, wrap some kitchen paper towel around the big end and secure it with tape. Then run the crankshaft with a motor drive and turn on the drip feed lubricator. See if the oil gets through to the towel.

Was this method ever used in full size? On locos the lubricator was mounted on the big end. On many stationary engines, there was a ring beyond the end on the crankshaft and concentric with it, the inside of the ring being a channel. Oil was dripped into the channel and tubed from there to the big end. That clearly avoids the problem. I'm not sure what marine practice was on multi-cylinder engines which, unlike locos, couldn't be stopped to replenish big end lubricators.