Viscosity of an oil is defined as its resistance to flow and Viscometer measures the flow. Monitoring viscosity is one of the most important components of any oil analysis program. Minute changes in viscosity at operating temperatures can be magnified to the extent that an oil is no longer able to provide adequate lubrication and efficiency in preventing friction between moving parts. - The temperature of the constant temperature bath is controlled by the temperature controller, and the refrigeration and heating parts compensate each other to achieve heat balance and maintain a certain accuracy in controlling the bath temperature. The instrument can install two samples for test at the same time. The constant temperature bath is equipped with a stirring motor to make the temperature in the whole constant temperature bath uniform.