What was found
BOI FLIGHT NR 2422: AFTER TAKEOFF, OIL TEMP CONTINUED TO CLIMB THRU ABOUT 15000 FT. TEMP WAS ABOUT 90 DEG. AFTER LEVEL OFF WITH CRUISE POWER SET, TEMP FLUCTUATED FROM 97 TO 86 AT ABOUT 1 MINUTE AT A TIME. IT WAS ABOVE 90 FOR THE FIRST 30 MINUTES OF FLIGHT. AFTER THAT IT STABLIZED AT 77-78. DURING TAXI IN, IT CLIMBED AGAIN TO 88. MAINTENANCE REMOVED AND REPLACED THE NR 1 OIL COOLER AIR OUTLET FLAP ACTUATOR IAW Q400 AMM 79-21-31-000-801 AND 79-21-31-400-801. OPS CHECK OF THE ACTUATOR WAS GOOD. AIRCRAFT RETURNED TO SERVICE.