As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PILOT REPORTED ON POST FLIGHT INSPECTION, DISCOVERED OIL ON OUTSIDE OF ENGINE COWLING, DRAINING FROM ENGINE DECK DRAIN LINES AND SMOKE COMING OFF OUTSIDE OF EXHAUST DUCT AND OIL ON OUTSIDE OF THE ENGINE. MECHANIC FOUND B-NUT VENT LINE LOOSE AND DISCONNECTED. CLEANED AREA AND REINSTALLED OIL VENT LINE PER ENGINE MANUAL. MOC OK. NO DEFECTS. BIS