As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ENROUTE, THE NBR 4 ENGINE EXPERIENCED OIL LOSS AND FLUCTUATING OIL PRESSURE. THE ENGINE WAS SHUT DOWN AND THE FLIGHT CONTINUED TO DTW WITHOUT FURTHER INCIDENT. VISUAL INSPECTION REVEALED OIL IN NR 4 ENGINE TAILPIPE. THE ENGINE WAS REPLACED AND CHECK WAS NORMAL.