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. In a wet-sump system, oil is kept in the sump ready for the next use. In a dry sump system, oil falls to the bottom of the engine and a scavenge pump sends it to an oil tank.
Most 2-stroke gasoline engines use a set gasoline-oil mixture for lubrication. As the air, fuel and oil enter the crankcase, the fuel evaporates, leaving behind enough oil to keep parts coated and lubricated.
An oil injection system doesn't need the oil and gasoline mixed manually. An engine-driven oil pump takes oil from a tank and pumps a measured amount directly into the engine where it mixes with the fuel and lubricates the internal engine parts.
In addition to normal internal lubrication, the rotary engine uses oil injection. A pump injects a measured amount into the intake manifold. Oil from these nozzles goes to the engine and lubricates the rotor seals.
