| SAE | Society of Automotive Engineers |
| SAN | Strong Acid Number |
| SAPS | Sulfated Ash, Phosphorus, Sulphur |
| SASH | Sulfated ASH |
| SAT-NAV | Satellite Navigation system |
| SCR | Selective Catalytic Reduction |
| SCS | Side Crash Sensor |
| SCTM | Seatbelt Timer Control Module |
| SDX | Solvent Dewaxing |
| SEMA | Specialty Equipment Market Association |
| SFI | Sequential (multiport) Fuel Injection |
| SFPP | Simulated Filter Plugging Point |
| SG | Single Grade (monograde) |
| SHED | Sealed Housing Evaporative Determination |
| SHPD | Super High Performance Diesel (oil) |
| SI | Système International (system of units) |
| SIAB | Side Impact Air Bag |
| SIB | Sulfurized IsoButylene |
| SIDI | Spark Ignition Direct Injection |
| SIP | Styrene Isoprene Co-Polymers |
| SLBOCLE | Scuffing Load Ball On Cylinder Lubricity Evaluator |
| SO2 | Sulphur Dioxide |
| SOF | Soluble Organic Fraction |
| SOHC | Single Overhead Camshaft |
| SRS | Supplementary Restraint System |
| SSI | Shear Stability Index |
| SSM | Suspension Steering Module |
| STOU | Super Tractor Oil Universal |
| SULEV | Super Ultra-Low Emission Vehicle |
| SUV | Sport Utility Vehicle |
| SWB | Short Wheel Base |
