ISO Viscosity Explained


Not all ISO’s are created equal

Each day we get that one or two phone calls where a customer says, “I need an ISO 68″; to which we reply the standard response, “Do you mean hydraulic oil ISO 68?”  We almost always get “It doesn’t matter, just any 68″.  ISO represents the viscosity of the fluid inside (or in layman’s terms the thickness of the fluid).  What it does not tell us is what “type” of fluid you need.  You may be needing the most popular (for us anyway) hydraulic fluid, or it could be a Chevron Meropa ISO 68 for a gear lubricant application; or we might even hand you a Chevron Cetus Hipersyn ISO 68 which is a synthetic compressor oil.

It’s what is added to the base stock that creates the fluid for a specific application (or applications).  ISO + Viscosity is used to break down different fluids by viscosity or thickness in the SAME FAMILY of products.  For instance, in the base Chevron Hydraulic Oil AW ISO product; the fluids come in a few “viscosities or thicknesses” of lubricant built specifically for hydraulic fluid applications such as ISO 32, ISO 46, and ISO 68.   You would not want to use any of these products where the OEM required a synthetic compressor fluid or a gear lubricant.

With most of the major oil companies going to a “proprietary” naming system like Meropa, Rando HD, Cetus, and many more, it’s best to know as much information about what application you’re putting this fluid in as well as the ISO/Viscosity of the fluid you need.