| Type | Reason for Use |
| Detergents, Dispersants | Keep Sludge, carbon and other deposit Precursors suspended in the oil, hence maintain engine cleanliness |
| Oxidation Inbitors | Prevent or control oxidation of oil, Formation o fvarnish, sludge, and Corrosive compounds. Limit viscosity Increase. |
| Alkaline Compounds | Neutralize acids, prevent corrosion from acid attack. |
| Extreme Pressure (EP) | Form protective film on lubricated parts. |
| Anti-wear, Friction Modifiers | Reduce wear, prevent galling and seizing |
| Rust Inhibitors | Prevent rust on metal surfaces by forming protective surface film or neutralizing acids |
| Metal Deactivators | Form film so that metal surfaces do not catalyse oil oxidation. |
| Viscosity Index Improvers | Reduce rate of viscosity change with temperature, reduces fuel consuptio. Allows easy cold starting. |
| Pour point Depressants | Lower "freezing" point of oils, assuring free flow at low temperatures. |
| Anti-foamants | Reduce foam in crankcase and blending. |