Hydraulic Oil Viscosity Reference Chart
Viscosity of the oil is a crucial property of a lubricant, a change in temperature will lead to a change in viscosity. A realisation of how much of an effect temperature has on the oil can be shown on the oil viscosity graph. Keeping your oil at the right temperature will maximise the lifetime of your machinery and protect against wear and corrosion.
Always try to maintain the desired oil temperature when your machinery is not in operation.