wet and dry sump systems are used in fours stroke cycle engines. The wet sump system is employed in relatively small engines, such as automobile engines, while the dry sump system is used in large stationary, marine and aircraft engines.

In wet sump system the bottom of crankcase contains an oil sump (or pan) that serves as the oil reservoir. Oil dripping from the cylinders and bearing flows by gravity back into the wet sump where it is picked up by a pump and re-circulated through the engine lubricated system.

In this system there is no reservoir as the oil required for lubrication remains in the circulation only.

In dry sump engine, the oil for lubrication is stored in a separate tank and is provided to the piston by the use of multiple vacuum pumps and rails. This allows for lighter lubrication system and this system performs better in racetrack conditions. Even formula 1 cars use this system to lubricate their engines.

The wet sump system uses the base of the crankcase as a reservoir for oil storage. This oil is actively transported to the top and then fed to the piston bearings. This pump is simple in design and is used by most of the commuter cars. It has a simpler design, uses a single pump and performs well under everyday road conditions.