What was found
CABIN FILLED WITH OILY SMELLING SMOKE AFTER APU STARTED ON GROUND. SIGNIFICANT DROP NOTED ON APU OIL LEVEL. CHECKED APU OIL LEVEL FOUND TO BE JUST BELOW THE ADD OIL LINE, STARTED APU AND RAN OIL AIRCONDITIONING AT DIFFERENT TEMPERATURE SETTINGS. COULD NOT DUPLICATE OIL SMELLING SMOKE IN THE CABIN. REMOVED COALESSER CLOTHS AND CLEANING THOROUGHLY REINSTALLED COALESSER CLOTHS AND REINSTALLED. OPERATED THE APU AND RAN AIR CONDITIONING PACKS. NO SMOKE OR SMELL NOTED. PERFORMED LEAK CHECK, NO LEAKS NOTED. ALL WORK PERFORMED IAW CE750 MM 12-10-01.