Every engine requires a certain amount of oil flow to keep the bearings, camshaft, valvetrain and other moving parts lubricated. Oil forms a barrier that prevents metal-to-metal contact and reduces friction and wear within the engine.
In the bearings, it forms a wedge that actually lifts and supports the crankshaft and camshaft as they rotate. Oil also serves as the primary means of cooling the bearings as well as the pistons. What