What was found
WHILE INVESTIGATING SUSPECTED APU OIL LEAKS APU FILTER (UNREADABLE), BYPASS BUTTON FOUND EXTENDED. GROUNDED - YES. DETERMINED FLUID ON THE APU EXHAUST CONE TO BE DEICE FLUID NO OIL LEAKS APU. REPLACED APU LUBE FILTER ELEMENT REF B737-900 AMM 49-91-12 INDICATOR POPPED AGAIN, PER AMM 49-91-13 REPLACED OIL FILTER INDICATOR PERFORMED LEAK AND OPS CHECK OF FILTER AND INDICATOR REMAINS SET ACFT OK FOR SERVICE SERVICED APU OIL TO FULL REF AMM 12-13-31 ETOPS OIL SERVICED.