As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING THE POST FLIGHT CHECKLIST ON DEC 10TH IT WAS DISCOVERED THAT THE OIL LEVEL FOR THE NR 1 ENG WAS BELOW THE INSPECTION SIGHT GLASS WITH OIL STREAKING PRESENT IN THE BYPASS DUCT. THE TROUBLESHOOTING FOR THE DEC 10TH OIL LEAK EVENT FOUND THAT THE OIL LEAK WAS A RESULT OF THE FAULT WITH THE NR 4 BEARING CARBON SEAL. SEVERAL DEFECTS WERE NOTED IN THE PLASMA COATING SEALING SURFACE OF THE CARBON SEAL RUNNER.