How is vacuum already created in the crank case?
How is there a vacuum in the crankcase without a pump or similar? There isn’t. And it has to do with pressure differential. Nothing gets “sucked” off of anything. To make it simple, the second ring is a scraper. It scrapes the oil off the cylinder wall. The oil ring catches the oil and sends it through the holes or slots in the piston back to the crankcase. What causes that is a pressure differential. The difference in pressure between the high pressure (combustion pressure) and the relative pressure in the crankcase. The higher the pressure differential, the more effective the rings are. The more effective the rings are, the thinner they can be. The thinner they are, the more power you make. There isn’t a vacuum in the crankcase unless you make a vacuum in the crankcase.
from the pistons moving down, its not a constant vacuum. you need a breather on your valve cover don't you? the vacuum is not at the bottom of the pan like with a pump. and if the rings are getting sucked tight to the cylinder walls which is the purpose of a vacuum pump for sure its drawing the oil to the bottom of the pan off the cylinder walls along with oil from the rest of the system. street motors dont get freshened like race motors do, that is why I believe running a pump on the street would result in a engine worn out prematurely.