Hydraulic oil can be called the most widely used industrial oil, therefore, due to its high consumption and diverse applications and working conditions, this oil is also highly diversified. Indeed, hydraulic oil plays a role in the energy transfer system, and if this oil gets into trouble, this task is not well done and the system faces a malfunction or stall. In general, tasks that are expected from a hydraulic oil are lubrication, power transfer, friction and wear, protecting the rust of the system components and adapting to all components of the system. Hydraulic oils are heavily sensitive to the contaminants they enter, and their physical and chemical properties change from contamination and difficult working conditions. Most people believe that hydraulic oil should have a certain function like motor oil, time or kilometers, while this applies to industrial oils, and in particular hydraulic oil, to the variety of equipment, the different conditions of operation and the type of work that oil in It depends on the system, therefore, it can not be defined for all types of hydraulic oils used in different vehicles when the same operation time is applied and is based on system operation.