A crankcase ventilation system having a crankcase ventilation filter and a filter drain. The crankcase ventilation filter vents blow-by gases from a crankcase and separates oil from the blow-by gases. The crankcase ventilation filter drain collects oil separated by the crankcase ventilation filter and returns the separated oil to the crankcase or another component of the engine. A nozzle is coupled to a pressurized oil supply and directs an oil jet into a mixing bore of the system, which draws the oil back into recirculation. A valve is coupled to the filter drain and is configured to prevent collected oil from reentering the crankcase ventilation filter through an opening that connects the filter drain to the filter.