Oil bath lubrication

Oil bath lubrication keeps moving parts immersed in an oil reservoir so they are lubricated continuously. Examples on motorcycles and similar machines include enclosed primary chain cases, fully enclosed final drive chains on older bikes and mopeds, some gearboxes and differentials, and oil-bath air filters on older engines and some ATVs.

The system is simple and protects well against dirt, but the oil must be at the right level and changed when it becomes contaminated with wear metal, water or dust.

Check the level through the sight glass or level plug and use the oil grade given in the manual. In wet-clutch engines the clutch also runs in oil, which is why motorcycle oil must be suitable for wet clutches (JASO MA/MA2).