All the details.

Oil circuit

The oil circuit of an engine needs to ensure that all moving mechanical parts and all places where friction between engine parts occurs are permanently supplied with a film of oil. In conventional car engines, the oil sump forms the reservoir for the engine oil circulating in the oil circuit. With the engine running, the oil pump ensures uniform oil pressure in the oil circuit. The engine's oil circuit also has an important task as a coolant in the crankcase.