An oil pan includes a pan structure forming a primary reservoir, and defining a PCV passage, and a PCV reservoir. The PCV passage includes an inlet for receiving fluid from a PCV drain of an engine block, and an outlet disposed vertically below the inlet of the PCV passage for discharging the fluid received from the PCV drain. The PCV reservoir includes a lower end disposed adjacent the outlet of the PCV passage, and an upper end disposed vertically above the lower end of the PCV reservoir and in fluid communication with the primary reservoir. The PCV passage and the PCV reservoir define a fluid flow path forming a fluid trap at the intersection of the outlet of the PCV passage and the lower end of the PCV reservoir, to keep the outlet of the PCV passage submerged during dynamic operation of the engine.