As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SMELL OF OIL IN CONDITIONED AIR IN DESCENT UNTIL ENGINE SHUTDOWN AT GATE. *S/D* RAN BOTH ENGINES AT IDLE AND HIGH POWER, WITH PACKS ISOLATED. NO SMOKE OR FUMES NOTED PER FIM 21-00-01. NOTED MUSTY ODOR WITH LEFT RECIRCULATION FAN, REPLACED FILTER, OPS CHECKED GOOD.