| Topic | Summary |
| Functions of oil |
Oil reduces unwanted friction. It reduces wear on moving parts, and helps cool an engine. It also absorbs shock loads and acts as a cleaning agent. |
| Viscosity |
Viscosity rating indicates flow rate of oil at a given temperature. There are many grades. Thin oils tend to be for cold conditions. Oil with improver is called multi-grade or multiple-viscosity oil. |
| Oil additives |
Different additives do different jobs. They can inhibit corrosion, foaming and oxidation, and act as dispersants. |
| Synthetic oils | Synthetic oils offer better protection against engine wear and can operate at higher temperatures. They have better low temperature viscosity, are chemically more stable and allow for closer tolerances in engine components without loss of lubrication. |