What was found
(CAN) LOW OIL PRESSURE FOLLOWING T/O AT FL130, THE LOW OIL PRESSURE WARNING LIGHT CAME ON. THE PILOT REDUCED POWER TO IDLE AND THE OIL PRESSURE CAME BACK NORMAL, HOWEVER UPON RE-ADVANCING THE THROTTLE, THE WARNING CAME BACK ON. POWER WAS REDUCED, EMERGENCY WAS DECLARED AND THE ACFT RETURNED TO THE POINT OF ORIGIN WHERE AN UNEVENTFUL LANDING WAS MADE.