An aircraft engine lubrication system has a vortex separator, a first pump line having a first pump, an inlet connected to a separated lubricant area at the outlet end of the separator, and an outlet connectable to the engine. A scavenge line is provided for returning lubricant from the engine to an inlet end of the separator. A lubricant tank is connected in fluid flow communication with the separator by a connection line. A second pump line having a second pump has an inlet connected to the lubricant tank and an outlet connected to the separator for pumping lubricant from the tank to the inlet end of the separator.