B737 flight crew reported #2 engine oil quantity decreased to zero followed by loss of oil pressure.

Attributes
ACN	1584846
Time
Date	201810
Local Time Of Day	0601-1200
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Light	Daylight
Aircraft 1
Make Model Name	B737-700
Operating Under FAR Part	Part 121
Flight Phase	Cruise
Flight Plan	IFR
Component
Aircraft Component	Oil Distribution
Person 1
Function	Pilot Not Flying First Officer
Qualification	Flight Crew Air Transport Pilot (ATP) Flight Crew Multiengine Flight Crew Instrument
Experience	Flight Crew Last 90 Days 439
Person 2
Function	Captain Pilot Flying
Qualification	Flight Crew Air Transport Pilot (ATP) Flight Crew Multiengine Flight Crew Instrument
Experience	Flight Crew Last 90 Days 382 Flight Crew Type 10000
Events
Anomaly	Aircraft Equipment Problem Less Severe

Narrative:

Approximately 120 to 160 miles east of ZZZ; the number 2 engine oil quantity slowly dropped and did not indicate secondary malfunctions. We had the jumpseat pilot check to see if he could see any signs of leaking; which he could not. We began to look at contingency fields; informed the company of our situation; and formed a plan of action 'just in case'. About five minutes after the oil quantity reached zero; oil pressure began to slowly drop. When the oil pressure continued its downward trend; the captain called for a precautionary divert to ZZZ. Approximately 25 miles from the field; the oil pressure intermittently flashed in the yellow and red so we shut the motor down and landed uneventfully at flaps 15.

Original NASA ASRS Text

Title: B737 flight crew reported #2 engine oil quantity decreased to zero followed by loss of oil pressure.

Narrative: Approximately 120 to 160 miles east of ZZZ; the number 2 engine oil quantity slowly dropped and did not indicate secondary malfunctions. We had the Jumpseat Pilot check to see if he could see any signs of leaking; which he could not. We began to look at contingency fields; informed the Company of our situation; and formed a plan of action 'just in case'. About five minutes after the oil quantity reached zero; oil pressure began to slowly drop. When the oil pressure continued its downward trend; the Captain called for a precautionary divert to ZZZ. Approximately 25 miles from the field; the oil pressure intermittently flashed in the yellow and red so we shut the motor down and landed uneventfully at flaps 15.

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.