| 1 | SOI | Southern Aviation Limited | Callsign: Soavair, | Z | AVCODES |
| 2 | SOI | Southern Aviation | | | ICAO1 |
| 3 | SOIA | SOSIDA SERVICES COMPANY LTD | | | SCAC4 |
| 4 | SOIE | STONE | | | SCAC4 |
| 5 | SOII | SCOTT OIL TRANSPORTATION INC | | | SCAC4 |
| 6 | SOIK | SIMON OIL INC | | | SCAC4 |
| 7 | SOIL | SOUTHERN ILLINOIS MOTOR XPRESS, INC | | | SCAC1 |
| 8 | SOIQ | STRATEGIC OPERATIONS INC | | | SCAC4 |
| 9 | SOIS | STOCKER OIL CO | | | SCAC4 |
| 10 | SOIT | SOUTHWEST ORIENT | | | SCAC1 |
| 11 | SOIV | SHERLOCK OIL | | | SCAC4 |
| 12 | SOIW | SAUNDERS OIL COMPANY INC | | | SCAC4 |
| 13 | SOIX | Standard Oil Co. (Indiana) | 8/1920-1/1952 | | NAKINA |
| 14 | SOIX | Standard Oil Co., series 591-1000 (Chicago & Alton R.R.) | 7/1923 | | NAKINA |
| 15 | SOIX | Sand Seed Service, Inc. | added 4/1980; eliminated 10/1992; 1/1994-7/2005 (not listed) | | NAKINA |
| 16 | SOIX | Standard Oil Co. (Indiana) | Jan-52 | | NRHS |
| 17 | SOIX | Sand Seed Service, Inc. | added 4/80; eliminated 10/92; 1/94-7/2000 | | NRHS |
| 18 | SOIX | *STANDARD OIL CO. (INDIANA) | | | PWRC |
| 19 | SOIX | +SAND SEED SERVICE, INC. | | | PWRC |
| 20 | SOIX | Sand Seed Service | | | RSRV |
| 21 | SOIY | SPRINT OIL COMPANY | | | SCAC4 |
