An oil sight glass is attached to a pump or turbine or gear box. It is used for visual oil monitoring or visual oil inspection. Visual oil monitoring, for instance, can be an early indicator of wear on the bearings in a pump. The condition of the oil, if clear or cloudy is also an early indicator of wear on the bearings. As a result, the pump can work more effectively. The oil sight glass alone will not prevent moisture from entering the reservoir. It will show water that has become emulsified in the oil. Using an oil slight glass on your pump can help to avoid a costly repair.