genee/rickie claim that oil pumps have to spin for some time to draw a prime.

I am trying to visualize how an oil pump draws a prime, particularly on oil at
say 15 degrees. In order to draw a prime the pump would have to evacuate the
air above the oil and below the pump, the difference in air pressure on the
evacuated side vs ambient air pressure leaves no more than a few pounds of
pressure total (can't be more than 14.7# total, for that is atmospheric
pressure). Then the oil would have to vaporize and then be drawn into the
pump, then to be compressed back to liquid to then be pumped to the bearings
needing pressure oil.

At even normal room temperature engine starts -- let alone cold weather engine
starts -- it would seem an oil pump requiring a prime to work might take
several minutes engine run time to begin to pump even small amounts of oil.
Anyone know how the engine designers allow for this and still make the engines
last more than a minute or so? Anyone know of which engine designs have oil
pumps that have to pull oil up before pressurizing it? How do they get the oil
volume on such oil pumps?