Menu Sub Menu Summary Oil Friction 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 Rating Viscosity rating indicates flow rate of oil at a given temperature. There are many grades.
Thin oils tend to be for cold conditions.
Additives Different additives do different jobs. They can inhibit corrosion, foaming and oxidation, and act as dispersants. In the splash lubrication system, a dipper or slinger splashes oil through the internal parts of the engine. Oil is also splashed up to the valve mechanism. . In force-feed lubrication, pressure forces oil around the engine.