What was found
(CAN) OIL PROBLEM IN-FLIGHT, AIRCRAFT RETURNED TO POINT OF DEPARTURE. POST-FLIGHT INSPECTION FOUND NO OIL IN THE ENGINE, BUT OIL WAS FOUND ON THE ENGINE COMPARTMENT. TEMPERATURE PROBE NUT FOUND LOOSE AND THIS WAS DETERMINED TO BE THE CAUSE OF THE OIL LEAK. THE SUBMITTER SUGGESTS THE TEMPERATURE PROBE NUT BE LOCKWIRED.