B737-800 captain reported refusing aircraft due to fumes on board during preflight at gate.

Attributes
ACN	1689122
Time
Date	201910
Local Time Of Day	0601-1200
Place
Locale Reference	ZZZ.Airport
State Reference	US
Aircraft 1
Make Model Name	B737-800
Operating Under FAR Part	Part 121
Flight Phase	Parked
Flight Plan	IFR
Component
Aircraft Component	APU
Person 1
Function	Captain Pilot Flying
Qualification	Flight Crew Instrument Flight Crew Air Transport Pilot (ATP) Flight Crew Multiengine
Events
Anomaly	Aircraft Equipment Problem Less Severe Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor

Narrative:

Fume/odor event at gate as indicated by oil fume odor probably related to APU bleed air. Pilots removed themselves from flying status. Aircraft removed from service. No passengers involved as problem was detected prior to boarding.

Original NASA ASRS Text

Title: B737-800 Captain reported refusing aircraft due to fumes on board during preflight at gate.

Narrative: Fume/odor event at gate as indicated by oil fume odor probably related to APU bleed air. Pilots removed themselves from flying status. Aircraft removed from service. No passengers involved as problem was detected prior to boarding.

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.