As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER LANDING AND WITHIN 3-5 MINS OF STARTING APU AND SELECTING THE BLEED AIR "ON", THE CABIN FILLED WITH SMOKE AND AN ODOR OF OIL. FOUND APU OIL OVER SERVICED. OIL COMING FROM GEAR CASE VENT TUBE. REMOVED 56 CC OF OIL. SERVICED OIL IAW RE-100CS, & MM 49-20-00. RAN APU WITH BLEED AIR TWICE. NO OIL LEAKS, SMOKE, OR OIL ODOR NOTED.