Hydraulic Oil is sold in numerous weights and viscosities.   We stock 5 gallon pails of ISO 46, also referred to as AW46.   We also stock an ATF as well.  ATF or Automatic Transmission Fluid is a red fluid that can also be used in hydraulic systems.  Please note which oil you need as they are NOT interchangeable.  Using the incorrect hydraulic oil may cause harm to your hydraulic system.