As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLIGHT 5367 - EN ROUTE CVG-OKC RECEIVED A LEFT ENGINE OIL PRESSURE MASTER WARNING, OIL PRESSURE FLUCTUATED BETWEEN 23-56 PSI. CREW DECLARED AN EMERGENCY AND RETURNED TO CVG WITHOUT INCIDENT. REPLACED THE -BB- AXIS CARBON SEAL AND RUNNER.