An oil cooling system for an aircraft engine, a bypass valve and an associate method of cooling aircraft engine oil are provided. The oil cooling system includes a heat exchanger having an inlet and an outlet. The inlet is in fluid communication with a first oil conduit to receive a first oil flow from the first oil conduit. The heat exchanger facilitates heat transfer from the first oil flow to another fluid. A flow restrictor defining a constriction is operatively disposed to restrict the first oil flow through the heat exchanger. A second oil conduit receives the first oil flow from the heat exchanger. A bypass oil passage provides fluid communication between the first oil conduit and the second oil conduit to allow a second oil flow received from the first oil conduit to flow to the second oil conduit and bypass the heat exchanger.