What was found
ON TAXI OUT, BOTH ENGINES SPOOLED DOWN FROM IDLE POWER AND PILOTS MANUALLY SHUT DOWN BOTH ENGINES WHEN THE GENERATORS DISCONNECTED AND THE RED OIL WARING INDICATIONS CAME ON. INSPECTED FUEL FOR CONTAMINATION AND SENT FUEL SAMPLES TO LOCAL FUEL PROVIDER FOR LAB TESTS, NO PROBLEM NOTED. SUSPECT ICING DUE TO EXTENDED GROUND TIME (10 DAYS) EVEN THOUGH ENGINES WERE RUN DAILY. HANGARED AIRCRAFT FOR 20 HRS, RAN ENGINES, ALL SYSTEMS NORMAL. PERFORMED CHECK FLIGHT, ALL SYSTEMS NORMAL.