| 1 | SWLX | Southwestern Tank Line Co. | 7/1932 | | NAKINA |
| 2 | SWLX | Southwestern Tank Line (Bartex Pipe Line Co.) | 7/1935 | | NAKINA |
| 3 | SWLX | Phillips Petroleum Co. | 7/1937-1/1946 | | NAKINA |
| 4 | SWLX | Essel Corp. | 10/1957; eliminated 10/1959 | | NAKINA |
| 5 | SWLX | Essel Petroleum Corp. | added 10/1957; added 10/1959; 4/1961-4/1970; eliminated 1/1974 | | NAKINA |
| 6 | SWLX | Essel Corp. | added 1/1974, 1/1975-1/1980; eliminated 10/1984 | | NAKINA |
| 7 | SWLX | Southwestern Tank Line Co. (Phillips Petroleum Co.) | Apr-38 | | NRHS |
| 8 | SWLX | Essel Corp. | 10/57; eliminated 10/59 | | NRHS |
| 9 | SWLX | Essel Petroleum Corp. | added 10/57; added 10/59; 4/61-4/70 | | NRHS |
| 10 | SWLX | Essel Corp. | 1/75-1/80; eliminated 10/84 | | NRHS |
| 11 | SWLX | *PHILLIPS PETROLEUM CO. [SOUTHWESTERN TANK LINE CO.] | | | PWRC |
| 12 | SWLX | *ESSEL CORPORATION | | | PWRC |
| 13 | SWLX | Essel Corporation | | | RSRV |
| 14 | SWLX | ESSEL PETROLEUM CORP | | | SCAC3 |
