B733 CREW REPORTS OIL LOSS WHILE IN CRUISE AND DECISION TO DIVERT AS OIL PRESSURE STARTS TO FLUCTUATE.

Narrative

ACFT HAD MAINT WORK FOR AN OIL LEAK FROM THE #1 ENG PRIOR TO THIS INCIDENT. WE FLEW THIS ACFT ON THE MORNING OF FEB/WED/07. DURING CRUISE AT FL340 JUST W OF GJT; THE FO NOTICED #1 OIL QUANTITY AT 32%. I SENT A MESSAGE TO MAINT TO REQUEST THEY LOOK AT THE ENG DATA. THEY RESPONDED THAT THE ACFT HAD AN OIL LEAK HISTORY SO IT'S POSSIBLE THIS WAS RECURRING. DISPATCH WAS ALSO NOTIFIED AT THIS POINT. AS A CREW; WE BEGAN REVIEWING WX ALONG THE RTE. OIL QUANTITY CONTINUED TO DECREASE AND WAS INDICATING 28%. ALL OTHER ENG PARAMETERS CONTINUED TO SHOW NORMAL. AT THIS POINT; NOTIFIED PURSER OF THE SIT AND ISSUED A CABIN ADVISORY. I ASKED MAINT IF WE COULD EXPECT TO SEE NORMAL INDICATIONS UNTIL THE TIME OIL QUANTITY WAS LOST. AT THIS POINT; STILL NOT CERTAIN IF TRUE LEAK OR INDICATOR PROB; HOWEVER; WITH HISTORY; SUSPECTED IT WAS A REAL LEAK. APPROX 75 NM FROM ZZZ; #1 OIL PRESSURE STARTED TO SHOW A DECREASE. DECIDED TO DIVERT TO ZZZ. DID NOT DECLARE AN EMER. IN RETROSPECT; SHOULD HAVE DONE THIS IMMEDIATELY. FO FLYING THE ACFT AND MYSELF COMPLETING NECESSARY DUTIES. ATC ISSUED DIRECT VOR DIRECT ZZZ. DECLARING EMER WOULD HAVE ALLOWED US TO GO DIRECT ZZZ IMMEDIATELY. STILL AMAZED AT HOW WORKLOAD INCREASES IN A 2-PLT JET; EVEN WITH LEAD TIME TO CONSIDER ACTION OPTIONS. GOOD COM AND IDEA EXCHANGER BTWN CAPT AND FO. DISPATCH DECLARED EMER FOR US WITH ATC. ON FINAL APCH; OIL PRESSURE WAS IN CAUTION RANGE. BY 500 FT ON FINAL; LOW OIL PRESSURE LIGHT BEGAN TO FLICKER ON AND OFF. LANDED WITHOUT INCIDENT AFTER NICE APCH BY FO. TURNED OFF RWY AND SHUT DOWN #1 ENG WHILE HAVING ACFT INSPECTED BY CFR UNITS. TAXIED TO GATE. IF FLT WAS; SAY 5 MINS LONGER; WE WOULD HAVE NEEDED TO SHUT THE ENG DOWN INFLT.