Date: 201911
Local time of day: 0601-1200
Location: ZZZ.Airport, US
Flight conditions: VMC
Aircraft: B777 Undifferentiated or Other Model
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Initial Climb
Airspace: Class A ZZZ
ATC / advisory: Center ZZZ
Aircraft component: Engine
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Pilot Flying; Captain
Reporter qualification: Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine; Flight Crew Instrument
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 Landed in Emergency Condition; Flight Crew Returned To Departure Airport; General Maintenance Action
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: On departure and climb out passing through 14000 ft.; crew observed a constantly high engine oil temperature indication; followed by an ECL (Electronic Checklist) annunciated procedure. We followed the ECL procedures and [requested priority handling] back to ZZZ. After communicating with Dispatch of our intentions; requesting overweight landing performance and manually reviewing aircraft landing performance; we communicated with our FAs (Flight Attendant) and passengers of our intentions. We performed on overweight landing on Runway XXL at ZZZ and taxied to the gate without further incidents.


Second narrative: On climb out around 15;000 feet we received an EICAS alert for 'left engine high oil temperature.' We noted the oil temperature was boxed and it was high. We ran the checklist which led us to reducing the thrust on the left engine to idle. It remained there for the duration of the flight. While the Captain flew; I took care of checklists; radios; automation; FMC tasks; ACARS tasks; ATC; and performance data in FM; as well as requesting from Dispatch. The Captain did brief FAs (Flight Attendants) and make a PA.We discussed landing overweight as I noted we would be about 32;000 lbs. over. We felt that given our performance data; and weather; not dumping fuel would be okay in this case. We [requested priority handling] and headed back towards ZZZ. With the engine at idle; the oil temperature was no longer boxed amber. The Captain did a tremendous job handling and prioritizing tasks while flying. At no time did I feel overloaded as we worked systematically through the issue as best we could. We had an otherwise normal landing; the brakes did not get above '2.5 - 3' and we taxied to the gate where we were met by [Company] and Maintenance for support.As an aside; I self-assessed and while I felt comfortable to do another 'normal flight' I was unsure of how I would I feel about doing another flight that may have another irregular issue to handle. I communicated this to [Company]; and was removed off the flight to deadhead to my next destination. I struggled making this choice initially; but reflecting back; it was the right move for me. Also; when talking to ATC it was a little difficult to communicate our 'state.' I wanted to let them know we were essentially on one engine; but the other engine wasn't in a fuel cut off state. So I did the best I could to communicate that while keeping it simple and clear. After we got to the gate; I mistakenly sent [the] electronic logbook entry as 'high engine oil pressure' by accident. It should have stated 'high engine oil temperature.' I sent another logbook entry in to correct this mistake. The Captain informed me he had only been on the airplane for about 5 months; and it was our first leg together. He did a great job managing the situation very calmly and in a very organized fashion.


Synopsis: B777 flight crew reported 'High Oil Temperature No. 1' EICAS annunciation during initial climb.