Here’s how the engine oil system works to lubricate the moving parts in your car’s engine. Here I demonstrate it on a 2001 Toyota Corolla 1ZZ-FE VVT-i engine.


Here’s what the oil pump looks like from the outside. Its driven off the crankshaft and takes oil from the pickup tube.


The oil pump acts like a centrifugal rotatory pump with a built in pressure regulator:

From the pump the oil heads to the filter. Here I cut an OEM Toyota filter open.

Paper filter, by pass valve and anti-drain back valve:

The oil then goes to lubricate the crankshaft, and connecting rods through holes drilled into the crank shaft.

The connecting rods have a small hole on the outside of the forging that squirts oil onto the piston walls and the connecting rod bushing at the top:



Next up the oil travels to the head where it lubricates the camshafts and VVT-I gear:


Here I cut open a camshaft:


Its actually hollow and easy to cut:



Finally after making its way through the oil system the oil drains back to the sump. Here I cut the oil pan open:



And you can see where the drain plug is, slightly higher than the bottom. Thus it’s a good idea to tilt the car back when changing oil.


And that’s pretty much the basics of engine oil lubrication on a 4 cylinder engine.

 

The oil pump you show I believe works not as a centrifugal pump (slinging the fluid outward by a centrifugal effect) but rather by changing the displacement of the cavities between rotating parts. The oil enters at the area where the cogs are spaced apart, then the oil is pressurized as the chambers get squished as the cogs come together at the bottom. A boat engine's water pump works the same way, only with flexible impeller blades that collapse and expand as they rotate. And I know, there's no such thing as "centrifugal" force, but it sure seems like there is.

The bearing surfaces in an auto engine are typically plain bearings, meaning that the machined bearing surfaces are microscopically separated by a very thin film of oil at all times--there is never any metal-to-metal contact. Such a bearing typically needs oil injected under pressure to work. By contrast, some small engines use ball or roller bearings, which can be satisfied with very low pressure or even just the oil splash from the rotating crank.