A wet sump is a lubricating oil management design for piston engines which uses the crankcase as a built-in reservoir for oil, as opposed to an external or secondary reservoir used in a dry sump design. A wet sump offers the advantage of a simple design, using a single pump and no external reservoir. Since the sump is internal, there is no need for hoses or tubes connecting the engine to an external sump which may leak. An internal oil pump is generally more difficult to replace, but that is dependent on the engine design.