| Business | Phone |
| Caltex Petroleum Corp 1825 I St Nw, Washington 20006 | (202) 429-2005 |
| Kuwait Petroleum Corp 401 9th St Nw # 770, Washington 20004 | (202) 783-9200 |
| Occidental International Corp 1717 Pennsylvania Ave Nw # 400, Washington 20006 | (202) 857-3000 |
| Quarles Petroleum Inc 2300 Pennsylvania Ave Se, Washington 20020 | (202) 584-2768 |
| Petroleum Engineering Co 4650 E West Hwy, Washington 20007 | (202) 298-4521 |
| Steuart Petroleum Co 1333 M St Se, Washington 20003 | (202) 675-4000 |