What was found
(CAN) JUST AFTER TAKEOFF THE NR 1 ENG OIL PRESS WARNING LIGHT ILLUMINATED & THE OIL PRESS GAUGE WAS FLUCTUATING BELOW 40 PSI. AN IN-FLIGHT ENG SHUTDOWN WAS CARRIED OUT & EMER DECLARED. THE ACFT SAFELY RETURNED TO THE DEPARTURE AIRPORT. INVESTIGATION FOUND THE ENG OIL LEVEL LOW, 3 LITERS OF OIL WERE ADDED & ENG RUNS CARRIED OUT. THE ACFT WAS RETURNED TO SERVICE. DURING THE MTC ENG RUNS IT WAS NOTED THAT THE NR 1 ENG OIL TEMP WAS SLOW TO RISE & TOOK 10 MINUTES TO REACH 45C AS COMPARED WITH 3 MINUTES FOR THE NR 2 ENG. WHILE THIS ANOMALY IN ITSELF WOULD NOT CAUSE THE OIL PRESS FLUCTUATIONS IT IS POSSIBLE THAT IT IS A CONTRIBUTING FACTOR. AFTER THE ACFT RETURNED TO A BASE THE NR 1 ENG OIL TEMP CONTROL VLV WAS REPLACED AS A PRECAUTION. ACFT TSN 54272, CSN 58716. OIL TEMP CONTROL VLV PN 45E04-2, TSN 17705, CSN 19916, TSO 5081, CSO 5859, TSR 3255, CSR 3690.