B737-800
Flight Crew Air Transport Pilot (ATP)
Aircraft Equipment Problem Critical
Flight Crew Returned To Departure Airport; General Declared Emergency; General Maintenance Action
Aircraft
During initial climb we noted an indication of low oil quantity (three quarts) in the left engine. Following QRH; we requested a level off at 8;000 feet MSL to allow possible engine 'oil gulping' to stabilize. After several minutes of level flight; the oil quantity remained low; fluctuating between two to three quarts. Other engine parameters were within limits. We decided to return to our departure airport. We declared an emergency with ATC and requested an ILS to Runway XX. I briefed the flight attendants and informed the passengers. Our jumpseat rider was very helpful. I asked him to notify the company and request an arrival gate. During this time; the engine oil quantity went to zero followed by the oil pressure going out of limits. Following the QRH; we shut down the left engine. Completed appropriate checklists and flew an uneventful ILS; landing and rollout on Runway XX. We had CFR personnel scan our left engine after landing; then taxied to the gate. Single engine flight time was approximately 10 minutes.
The Captain flew an ILS to Runway XX in VFR conditions. During the approach; the flight director steering bars were not working correctly; but the localizer and glideslope pointers were displaying correct information and we were VFR with the runway in sight; so we disregarded the flight director and continued the approach. Maintenance subsequently reported finding the Fuel-Oil Heat Exchanger leaking from the drain.
The flight crew of a B737-800 shut down the left engine shortly after takeoff due to loss of oil and oil pressure.  They declared an emergency and returned uneventfully to their departure airport.