How to replace the hydraulic oil of plywood hot press?

How to replace the hydraulic oil of plywood hot press?
plywood hot press
In any case, the hydraulic oil is replaced every year (refers to no more than 200 working days). Fluid cleaning is critical to the life of the hydraulic system and is regularly maintained for long life.
The recommended hydraulic oil standards are as follows:
ISO VG32 for winter, ISO VG46 for summer -20-65 °C, temperature -5-74 °C
VG32 indicator: center viscosity value 32mm2 / S (40 ° C)
VG46 indicator: center viscosity value 46mm2 / S (40 ° C)
  Special Note: When replacing important components, they should be purchased from the original factory to avoid improper operation of the system.
-------------END-------------