Narrative:

Last night I was scheduled to fly from ZZZ to ZZZZ. During my preflight review of the aircraft logbook; I noticed many entries for oil service on the left engine and that there was a maintenance watch for oil consumption as well. There were no signs of an oil leak during the preflight by my relief pilot and the consumption seemed to be internal use and under control; so I accepted the aircraft and we departed as scheduled. We had both engines full of oil at 21 quarts when we left the gate and both were normal after engine start and when we reached the takeoff position. After leveloff at our cruise altitude; the left engine showed 1 quart less than the right engine; so I started to monitor the oil levels closely. After about 90 mins of flight we were down to 14 quarts of oil in the left engine and we realized that if the consumption continued we would not have enough oil to reach ZZZZ. I decided to divert when the oil level reached 13 quarts and contacted dispatch to coordinate a suitable alternate. We decided to return to ZZZ and turned the aircraft around back to the north. The oil consumption increased at this point and to avoid an engine shutdown I changed the landing airport to ZZZ2. We declared an emergency; flew direct to ZZZ2. The oil had dropped to 5 quarts and I decided it was better to land overweight and get the aircraft safety on the ground than try to circle and dump fuel. We requested crash fire rescue equipment equipment to stand by for landing and made a normal approach and landing. The oil level was 4 quarts on landing and the landing was soft with a sink rate near 0 FPM. ZZZ2 maintenance found an oil line loose on the left engine and corrected the problem and completed an overweight landing inspection and we then continued the flight to ZZZ1 with no further problems.

Related reports:

Google
 

Original NASA ASRS Text

Title: A B767 ENG HAD EXCESSIVE OIL CONSUMPTION IN FLT. THE CREW DIVERTED TO A NEARBY ENROUTE ARPT WHILE ENG OIL REMAINED AVAILABLE.

Narrative: LAST NIGHT I WAS SCHEDULED TO FLY FROM ZZZ TO ZZZZ. DURING MY PREFLT REVIEW OF THE ACFT LOGBOOK; I NOTICED MANY ENTRIES FOR OIL SVC ON THE L ENG AND THAT THERE WAS A MAINT WATCH FOR OIL CONSUMPTION AS WELL. THERE WERE NO SIGNS OF AN OIL LEAK DURING THE PREFLT BY MY RELIEF PLT AND THE CONSUMPTION SEEMED TO BE INTERNAL USE AND UNDER CTL; SO I ACCEPTED THE ACFT AND WE DEPARTED AS SCHEDULED. WE HAD BOTH ENGS FULL OF OIL AT 21 QUARTS WHEN WE LEFT THE GATE AND BOTH WERE NORMAL AFTER ENG START AND WHEN WE REACHED THE TKOF POS. AFTER LEVELOFF AT OUR CRUISE ALT; THE L ENG SHOWED 1 QUART LESS THAN THE R ENG; SO I STARTED TO MONITOR THE OIL LEVELS CLOSELY. AFTER ABOUT 90 MINS OF FLT WE WERE DOWN TO 14 QUARTS OF OIL IN THE L ENG AND WE REALIZED THAT IF THE CONSUMPTION CONTINUED WE WOULD NOT HAVE ENOUGH OIL TO REACH ZZZZ. I DECIDED TO DIVERT WHEN THE OIL LEVEL REACHED 13 QUARTS AND CONTACTED DISPATCH TO COORDINATE A SUITABLE ALTERNATE. WE DECIDED TO RETURN TO ZZZ AND TURNED THE ACFT AROUND BACK TO THE N. THE OIL CONSUMPTION INCREASED AT THIS POINT AND TO AVOID AN ENG SHUTDOWN I CHANGED THE LNDG ARPT TO ZZZ2. WE DECLARED AN EMER; FLEW DIRECT TO ZZZ2. THE OIL HAD DROPPED TO 5 QUARTS AND I DECIDED IT WAS BETTER TO LAND OVERWT AND GET THE ACFT SAFETY ON THE GND THAN TRY TO CIRCLE AND DUMP FUEL. WE REQUESTED CFR EQUIP TO STAND BY FOR LNDG AND MADE A NORMAL APCH AND LNDG. THE OIL LEVEL WAS 4 QUARTS ON LNDG AND THE LNDG WAS SOFT WITH A SINK RATE NEAR 0 FPM. ZZZ2 MAINT FOUND AN OIL LINE LOOSE ON THE L ENG AND CORRECTED THE PROB AND COMPLETED AN OVERWT LNDG INSPECTION AND WE THEN CONTINUED THE FLT TO ZZZ1 WITH NO FURTHER PROBS.

Data retrieved from NASA's ASRS site as of May 2009 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.