THE OIL SKIMMER FUNCTION During cleaning, oil, grease and light dirt will raise to the surface of the water. If this is not removed, the cleaned components will become dirty as they are raised up through the surface. The surface skimmer function flushes the water surface after each cleaning cycle, before the basket is raised out of the tank. This ensures completely clean components after each cleaning cycle. The dirt, oil & grease removed from the surface is collected in the oil skimmer where oil and grease is skimmed off