What was found
DURING CLIMB NR 2 ENGINE OIL TEMP INDICATION READ 150. SWAPPED GAUGES FOR TROUBLESHOOTING, NO HELP. AFTER RETARDING NR 2 POWER LEVER, OIL TEMPERATURE DECREASED, ADVANCE POWER LEVER, TEMPERATURE INCREASED. NEVER EXCEEDED THE 15 MINUTES LIMIT. AIRCRAFT RETURNED TO KMIA AND LANDED OVERWEIGHT UNEVENTFUL. REMOVED AND REPLACED NR 2 ENGINE FUEL/OIL COOLER IAW DC8 MM 79-20-2, NO LEAKS NOTED. DURING OPS CHECK FOUND NR 2 OIL TEMP ERRATIC AND OSCILLATING. REPAIRED WIRE IAW MM 20-50-1 CHECK ELECTRICAL SYSTEM IAW MM 77-5-0 FOUND NORMAL. PERFORMED ENGINE RUN UP OPS CHECK NORMAL IAW MM 71-00. OVERWEIGHT LANDING INSPECTION PERFORMED IAW JC 6372 A-INSPECTION, NO DISCREPANCIES NOTED. AIRCRAFT RETURNED TO SERVICE.