As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) DURING WALK AROUND, AN OIL LEAK WAS DETECTED FROM NR 1 ENGINE. IT WAS DETERMINED THAT THE NR 1 OIL COOLER WAS LEAKING, LEAK APPEARED TO BE COMING FROM AFT UPPER CORNER COOLING FINS. THE OIL COOLER WAS REPLACED AND THE AIRCRAFT WAS SUBSEQUENTLY RELEASED FOR SERVICE (TC NR 20180102003).