Date: 201807
Local time of day: 1801-2400
Location: ZZZ.ARTCC, US
Flight conditions: VMC
Aircraft: B777 Undifferentiated or Other Model
Operator: Air Carrier
Operating under: Part 121
Mission: Passenger
Flight phase: Climb
Airspace: Class A ZZZ
ATC / advisory: Center ZZZ
Aircraft component: Oil Cooler
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Pilot Not Flying; First Officer
Reporter qualification: Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine; Flight Crew Instrument
Human factors: Confusion
Second reporter function: First Officer; Pilot Not Flying
Anomaly: Aircraft Equipment Problem Less Severe
Detector: Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Provided Assistance; Flight Crew Diverted; Flight Crew Landed in Emergency Condition; Flight Crew Overcame Equipment Problem; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Returned To Departure Airport
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: Upon climbout; approximately 18;000 feet; we encountered an EICAS (Engine Indicating and Crew Alerting System) message relating to a high oil temp on the left engine with an amber engine oil temp reading of approximately 165 C. This occurred just before breaks were to begin so fortunately all three crew members were on hand to attend to the abnormality. As a crew we divided the responsibilities up accordingly and began the process of running the appropriate checklists and reaching out to company personnel. Upon running the checklist it became apparent that a return to [the departure airport] was going to be the appropriate action. We conferred with Dispatch and Maintenance and then as a crew and determined that a return to [the airport] was indeed our best course of action. Once the decision was made we let the appropriate entities known that was going to be [the] flight's intentions. With Dispatch and Maintenance now in the know we turned our attention to informing ATC and calling the lead flight attendant to TEST him on the current situation/intentions. With the aircraft now turned in the direction of [the airport] and the High Oil Temp checklist complete we now as crew discussed whether to land overweight or dump fuel. We decided at our current weight; current weather in ZZZ; long runway options; and the best flying captain in ZZZ; that an overweight landing was not something that should keep us from getting on the ground sooner rather than later. We ran the overweight checklist and set the aircraft up for that scenario. Note: some confusion can arise from the overweight landing checklist if careful attention is not given to it; we ran it twice to ensure proper procedures were met. The remainder of the flight proceeded without event and the landing was smooth! The Ground Operations and folks who met us at the gate were great just an FYI! As a crew we had a debriefing discussion about how we felt things went and after what I felt was an honest crew critique our only topic we kept retouching on was the overweight landing decision. We all agreed however that it is a discretionary call that was properly considered and made comfortably by us a crew.


Second narrative: [Report narrative contained no additional information.]


Synopsis: B777 flight crew reported that an EICAS message 'High Oil Temp L' came on indicating the left engine had higher than normal oil temperature.