Date: 202110
Local time of day: 1801-2400
Location: ZZZ.Airport, US
Flight conditions: VMC
Light: Night
Aircraft: B737 Undifferentiated or Other Model
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Cruise
Airspace: Class B ZZZ
ATC / advisory: Tower ZZZ
Aircraft component: Powerplant Lubrication System
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: First Officer; Pilot Not Flying
Reporter qualification: Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine
Second reporter function: First Officer; Pilot Not Flying
Anomaly: Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Provided Assistance; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Returned To Departure Airport; Flight Crew Landed As Precaution; Flight Crew Overcame Equipment Problem; Flight Crew Inflight Shutdown; General Maintenance Action; General Flight Cancelled / Delayed
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: Approximately 45 minutes after going on break I was called back to the flight deck and informed that a loss in oil quantity on the number 2 engine subsequently resulted in a low oil pressure EICAS message. Maintenance Control and Dispatch were notified of the situation. The Checklist called for an engine shutdown due to the low oil pressure and a decision was made to return to ZZZ. We [requested priority handling] and we were given clearance to a lower altitude. We communicated our situation to the Purser using the acronym and made a PA to the passengers advising them of the situation and that we would be returning to ZZZ. We requested the ILS to the longest Runway XXR and landed at ZZZ without further incident. Airport Rescue and Firefighting followed us to Gate XX on the taxi in as well.


Second narrative: Departed ZZZ to ZZZ1 on flight XXXX. Shortly after reaching cruise altitude; we noticed a low oil indication on the #2 engine of 1 quart. All other engine indications were normal at the time; so we called Dispatch and Maintenance Control to get their input. While on the Sat Phone with them; the #2 oil pressure gauge started jumping around slowly bouncing lower. We made the decision to discontinue the flight and return to ZZZ. We informed ATC that we needed to return and they cleared us back to ZZZ. We then informed the flight attendants of the situation and called our Relief Pilot back to the flight deck. About 5 minutes into our return; the oil pressure gauge continued to drop lower and we got the low oil pressure warning indication. At that time we ran the appropriate checklist and secured the #2 engine. We then informed ATC; requested priority handling; and got a lower altitude. We then informed Dispatch/Maintenance Control of the situation; all while keeping our flight attendants and passengers updated. Then we decided to dump fuel; informed ATC when we started and stopped dumping. Shot the ILS XXR approach in ZZZ because the winds were favoring that runway and it was the longest. Landed without incident. Taxied to Gate XX and deplaned the passengers.


Synopsis: Flight Crew reported a loss of #2 engine oil quantity; resulting an in flight shut down of the engine and a precautionary landing.