O
- Oil and Gas Development Corporation (OGDC) — Pakistan
- OLCO Petroleum Group, Incorporated — Ontario and Quebec, Canada
- Olerex — Estonia
- Olís — Iceland
- OK
- OKQ8 — Sweden, joint venture with Q8.
- OK Benzin — Denmark
- OMV — Austria, Germany, Eastern Europe
- Orkan Bensín — Iceland
- Avanti — Austria, discount brand
- Petrom — Romania
- Oro Negro — Cuba
Read more about this topic: List Of Automotive Fuel Brands