B737 FLT CREW EXPERIENCES OIL FILTER BYPASS LIGHT CLIMBING OUT OF FL260 AND AFTER COMPLYING WITH PROCEDURES; RETURNS TO DEPARTURE ARPT.

Narrative

DURING CLBOUT THROUGH FL260 THE CAPT ANNOUNCED WE HAD AN OIL FILTER BYPASS LIGHT ILLUMINATED ON THE #1 ENG. I WAS FLYING AND CONTINUED TO DO SO; WHILE ALSO TAKING OVER ATC COMS. THE CAPT REFED THE FM AND ACCOMPLISHED THE OIL FILTER BYPASS CHKLIST WHILE I REQUESTED TO LEVELOFF AT FL280 WITH ATC. WHILE FOLLOWING THE CHKLIST WE RETARDED THE L THROTTLE TO EXTINGUISH THE LIGHT. AT IDLE AFTER A FEW SECONDS THE LIGHT WENT OUT. I SET UP THE ACFT FOR THE DRIFT-DOWN AND REQUESTED A LOWER ALT WITH ATC. THE CHKLIST DIRECTED TO LAND AT THE NEAREST SUITABLE ARPT SO I REQUESTED A PRESENT POS HOLD WITH ATC ABOUT 60 NM N OF ZZZ. THE CAPT FINISHED THE CHKLIST AND RAN THE DRIFT-DOWN CHKLIST WHILE IN THE HOLDING PATTERN. I DECLARED AN EMER WITH ATC AND THE CAPT ATTEMPTED TO CONTACT DISPATCH. IT TOOK SEVERAL FREQ CHANGES TO GET A FREQ THAT WE COULD COMMUNICATE WITH DISPATCH ON. WE DECIDED TO DIVERT TO ZZZ WITH DISPATCH CONCURRENCE. THE CAPT ADVISED THE FLT ATTENDANTS OF OUR SITUATION AND ASKED THEM TO DO A CABIN ADVISORY. HE ALSO SPOKE TO THE PAX AND LET THEM KNOW OF OUR INTENTIONS. WE SET UP FOR THE APCH IN THE HOLDING PATTERN AND REVIEWED THE ABNORMAL LNDG CONFIGN LNDG DISTANCE AND BRIEFED THE FLAPS 15 DEG APCH AND LNDG. WE COORDINATED TO HAVE EMER VEHICLES STANDING BY IN ZZZ; AFTER THE APCH DSCNT CHKLIST WAS DONE THE CAPT TOOK THE AIRPLANE AND LANDED UNEVENTFULLY WITH THE L ENG AT IDLE. WE TAXIED TO THE GATE AND SHUT DOWN NORMALLY. THE STATION WAS WELL PREPARED AND READY FOR OUR ARR.