What will overheating do to my hydraulic oil ?
How hot is too hot for a hydraulic system? It depends mainly on the viscosity and viscosity index (rate of change in viscosity with temperature) of the oil, and the type of hydraulic components in the system.
As the oil’s temperature increases, its viscosity decreases. Therefore, a hydraulic system is operating too hot when it reaches the temperature at which oil viscosity falls below that required for adequate lubrication.
Apart from the issue of adequate lubrication, the importance of which cannot be overstated, operating temperatures above 82 degrees Celsius damage most seal and hose compounds and accelerate degradation of the oil. But for the reasons already explained, a hydraulic system can be running too hot well below this temperature.