What was found
DURING THE FINAL STAGES OF A HIGH ALTITUDE 3 HOUR FLIGHT WHILE MANEUVERING BELOW 10,000 FEET WITH THE THROTTLES PULLED BACK NEAR IDLE TO DESCEND AND SLOW DOWN A STRONG OILY MUSTY ODOR PERMEATED THE COCKPIT AND CABIN. UPON ARRIVAL AT AIRCRAFT, LEFT AND RIGHT ENGINE OIL LEVELS WERE CHECKED AND FOUND TO BE LOW. APU OIL LEVEL WAS ALSO CHECKED USING THE DIP STICK AND FOUND TO BE OVER SERVICED. GAINED ACCESS TO LEFT AND RIGHT ENGINE BLEED AIR PIPES AND CHECKED FOR OIL RESIDUE IN PIPES, NO RESIDUE WAS NOTED AND REINSTALLED PIPES TO ORIGINAL CONDITION. ACCESSED MAINTENANCE LOG AND IT WAS NOTED THAT THE APU OIL LEVEL WAS SERVICED. GAINED ACCESS TO ACM WATER SEPARATOR AND REMOVED SOCK AND CLEANED IN ACCORDANCE WITH MAINTENANCE MANUAL 12-19-00. REINSTALLED SOCK. SERVICED LEFT AND RIGHT ENGINE OIL WITH 1/2 QUART FOR EACH ENGINE IN ACCORDANCE WITH MAINTENANCE MANUAL 12-11-02. ACCOMPLISHED ENGINE RUN AND NO SMELL WAS NOTED FROM EITHER ENGINE.