Narrative:

Approximately 2 hours into our flight from ZZZZ to ZZZ I noticed the number 1 engine oil quantity decreasing and notified my captain who was the pilot flying. We complied with the QRH non annunciated checklist for decreasing/low oil quantity which basically says to monitor and look for other indications and or an ECAM warnings. When the oil quantity dropped below 3 quarts we made satcom communications with maintenance and dispatch and concurrently made the decision to return to ZZZZ because the plane had just come out of a heavy check and the oil quantity showed a slow; methodical decrease in quantity. We [advised ATC] on the turn back as the oil quantity was now reading 0 (zero). We decided; with concurrence of maintenance and dispatch; to run the engine at a minimum power setting; which also complies with the QRH. Approximately an hour and a half later and an hour from ZZZZ the oil pressure began to fluctuate and fall to the top of the red line band on the oil pressure indicator (approximately 70 psi). With the concurrence of maintenance control; we shut the engine down to prevent any impending damage. We returned to ZZZZ for an uneventful overweight and auto-land to runway xxr. Post flight inspection of the number 1 engine did reveal a crack in a repair weld to the fuel/oil cooler and no oil left in the number 1 engine reservoir. We flew the same aircraft the following day after repairs were made by ZZZZ mechanics and returned to ZZZ uneventfully.

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Original NASA ASRS Text

Title: A330 First Officer reported observing the oil quantity decreasing on one engine and completed the appropriate troubleshooting checklists. The oil quantity continued to decrease and when it reached a level which affected the oil pressure they shut down the engine; returned to the departure airport; and made an uneventful landing.

Narrative: Approximately 2 hours into our flight from ZZZZ to ZZZ I noticed the Number 1 engine oil quantity decreasing and notified my Captain who was the Pilot Flying. We complied with the QRH non annunciated checklist for decreasing/low oil quantity which basically says to monitor and look for other indications and or an ECAM warnings. When the oil quantity dropped below 3 quarts we made SATCOM communications with maintenance and dispatch and concurrently made the decision to return to ZZZZ because the plane had just come out of a Heavy Check and the oil quantity showed a slow; methodical decrease in quantity. We [advised ATC] on the turn back as the oil quantity was now reading 0 (zero). We decided; with concurrence of maintenance and dispatch; to run the engine at a minimum power setting; which also complies with the QRH. Approximately an hour and a half later and an hour from ZZZZ the oil pressure began to fluctuate and fall to the top of the red line band on the oil pressure indicator (approximately 70 psi). With the concurrence of Maintenance Control; we shut the engine down to prevent any impending damage. We returned to ZZZZ for an uneventful overweight and auto-land to Runway XXR. Post flight inspection of the number 1 engine did reveal a crack in a repair weld to the fuel/oil cooler and no oil left in the number 1 engine reservoir. We flew the same aircraft the following day after repairs were made by ZZZZ mechanics and returned to ZZZ uneventfully.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.