The active word is "slings". It doesn't just block the oil from running that way, like a dam, but as the crankshaft turns,the slinger helps any oil that comes in contact with it to fly away.

I cannot understand why this is so hard to grasp. Oil slingers are used all the time in industrial equipment. It is not a Mopar-only concept.

The reason one can leave it off is that the lip seals are pretty good these days and can handle having some oil on them.

The front oil control device that amuses me is the stationary sleeve fitted around a sort of screw thread rotating with the crankshaft. Rotation of the crank turns the thread that pushes oil back into the engine. It's not really a seal, but it does keep leakage to a minimum. It can also propel debris into the engine.

R.