What was found
(CAN) OIL COOLER (P/N 649479) WAS DELIVERED AND INSTALLED WITH AN OVERHAULED ENGINE. AS WINTER APPROACHED THE ENGINE OIL TEMPERATURE, DURING CRUISE, BEGAN TO DROP. WITH AMBIENT AIR TEMPERATURE -20 DEGREES CELSIUS, THE ENGINE OIL TEMPERATURE WAS BELOW THE BOTTOM OF THE GREEN ARC, ON THE COCKPIT GAUGE. ORIGINAL EQUIPMENT OIL COOLER (HARRISON P/N 636900R). REPLACED CONTINENTAL COOLER AND THE PROBLEM WENT AWAY.