What is the right viscosity for a hydraulic lubricant?

Viscosimetric properties

• The right viscosity

Hydraulic equipment functions in a defined viscosity range. It is therefore important to supply a hydraulic oil of the right viscosity in order to guarantee optimum functioning of the installation.
Insufficient viscosity leads to breakdowns in the oil film and therefore wear on the moving parts. In addition, losses are increased.
On the other hand, an excessive viscosity has a negative impact on efficiency, heat exchanges and may lead to cavitation phenomena in pumps.
Note: the impact of pressure on viscosity should not be forgotten (viscosity increases with pressure).

• High viscosity index - for applications over a wide temperature range

For use in varying climatic conditions, it is important to guarantee the right viscosity over the whole temperature range, hence the importance of the viscosity index for these applications.
The higher the viscosity index, the lower the variation in viscosity in relation to temperature. A high viscosity index enables proper functioning over a much wider temperature range.