MD-11
Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Flight Crew Last 90 Days 124; Flight Crew Total 11195; Flight Crew Type 1100
Aircraft Equipment Problem Critical
Flight Crew Diverted; Flight Crew Landed As Precaution; General Maintenance Action
Aircraft
Flight ABC; ZZZ to ZZZ1 divert to ZZZZ. It began when the Captain said; 'Look at the #2 oil quantity.'  This occurred around 3 hours into the flight.  I believe it was indicating around 9 quarts while the other two engines were indicating normal quantities; around 17-19 quarts each.  As we observed the #2 oil quantity; it continued to drop to 8 quarts then 7 quarts.  We talked about a divert to ZZZZ; about 45 minutes south of our position.  We also discussed continuing to ZZZ1 and that we would be over the mountains in about an hour.  The Captain then checked our drift down altitude based on our weight and found that we would have been very close to the MEA for two engines had we continued toward ZZZ1.  Based on the rate of oil quantity decline; we calculated we had about an hour until we were going to have to shut down the #2 engine. The Captain then used SATCOM to contact Dispatch and Maintenance Control.  We were all in agreement to divert to ZZZZ.  We received the amended release at XA:58Z and; at the same time; a clearance from ATC to proceed direct to ZZZZ airport.  We did inform ATC that we were indicating a low oil quantity in our tail engine but we were not declaring an emergency because everything else was normal.  We just wanted to do a precautionary landing and have our engine checked out.  During the descent; the oil quantity kept dropping from 6 to 5 quarts.  Then during the approach; the quantity fluctuated between 5 and 4 quarts.  Just after touchdown; as the reverses came open; the quantity dropped from 5 to 4 with an amber box; to 3 just as the nose wheels touchdown.  That's when the Captain commanded shut down #2 now.  We landed at XB:41Z and parked at XB:51Z.  We went to the back of the plane and found fresh oil drops all over the ground in probably a 10 foot square area and could see oil drips hanging off the bottom of the engine.When this situation began; We had our jumpseater come up and look up engine oil quantity low in the AOM [Aircraft Operations Manual].  It was very vague on what actions to take - only shut down when oil temp and press become abnormal.  We wanted to get on the ground before we had to shut down the engine.  It did say the oil quantity will turn an amber box at 4 quarts; which it did upon landing.  We did agree early on in our discussions that we would shut it down if it turned amber to prevent damaging the engine.  We chose ZZZZ due to the fact that it was the closest [Company] airport.  We believed that had we continued to ZZZZ1; we would have had an in flight shutdown of the #2 engine and would have had to declare an emergency; with possible damage to the windmilling engine with no oil.   The Captain used excellent CRM having all 3 of us work the problem; discussing the risks; setting bottom lines and making safe; prompt decisions to avert an engine shutdown; or worse; over mountainous terrain with a minimal margin of safety; and possible engine damage.
MD11 pilot reported oil issue in number two engine. Aircraft was diverted to check on problem.