How do you know if you’re using the right Hydraulic Oil?

Hydraulic Fluid

There is a wide range of options available in the market right now. But for optimum performance and longevity of your machines, it is imperative that you carefully choose the right one. It is only because of wrong lubricant selection that often leads to a sudden and drastic reduction in its operational efficiency which results in increased maintenance costs and frequent disruptions. It is everyone’s nightmare. Don’t worry, we will answer and clear most of your doubts here through this article and help you make the right choice. The thing is with hydraulics is that there are two primary factors that you should always keep in mind:

  • The viscosity grade
  • The hydraulic oil type (denoted as AW or R&O)

These factors are typically ascertained by the type of hydraulic pump deployed in the system, the operating temperature and also the system’s operating pressure which plays a crucial role in the performance of the machines.

Types of Hydraulic Fluids available

Hydraulic fluid has a crucial role in the seamless operation of any system. These roles often vary from being a heat transfer medium or being a power transfer medium or a lubrication medium depending on the type of machine. The chemical composition of any hydraulic fluid can generally take many forms while you are selecting it for specific reasons or applications. It may range from fully synthetic (which is to handle extremely drastic temperatures and wild pressure swings) to water-based fluids (which are used in applications which are flammable and there is a high risk of fire).

A synthetic fluid, a petroleum fluid and water-based fluids are the most common forms of the fluid types. These fluids are generally needed to ensure optimal and seamless operations.

Which Hydraulic Fluid Should You Use?

Most hydraulic systems will function satisfactorily with the help of a variety of fluids. These generally include engine oil, automatic transmission fluid and oil formulation created specifically for the hydraulic compartment. Now the question is how you do know which type of fluid is best for the given application? Finding a definitive recommendation that fits all types of hydraulic equipment in all types of applications may be difficult.
Hydraulic oil has a crucial role to play. It’s often a power transmission device, acts as a lubricant, also a heat transfer medium and even sometimes as a sealant for some hydraulic components.

What makes it all the more troublesome is the long list of hydraulic oils which are available in the market today and that can make things very confusing? We have carefully compiled some of the most important factors you should keep in mind while choosing the best hydraulic fluid although as we said no imposition is perfect because there are many types of tools and machines so ideally you’d have to go for the right combination but still we would share these best practices with you to make the selection of hydraulic oil or hydraulic fluid a little bit easier for you.

Let’s have a look at some of the key factors:

  • The viscosity grade of the oil (provided by OEM manufacturer)
  • whether the oil is required to be High Viscosity Index
  • whether the oil is required to have additional Anti-wear properties
  • whether the oil is required to have additional rust and oxidation properties
  • whether the oil is required to be Zinc free
  • whether the oil is required to be Mineral or Synthetic based
  • whether the oil is required to be biodegradable
  • whether the oil is required to be non-detergent oil

All of the above information can be found in the OEM manufacturer’s owner’s manual. There is no golden combination as you have to check the instructions or the performance history to find out what works well. Ask engineers or experts and they would tell you to consider the hydraulic fluid as the single most important component for your machine. This should not be something to be purchased seeing the price alone and there is a lot more to it.

In conclusion, you should not compromise on the selection of right hydraulic fluid and go with options that translate into the smooth performance of the applications that you have. You might want to consult an expert before selecting the hydraulic oil/fluid on your own.


  1. It’s interesting to learn that we’d check the oil’s anti-wear properties and if it has additional ones. My brother needs to find lubricant oil for his newest machine this week before the machine gets damaged. I appreciate your intake on what to consider when buying hydraulic oil, and my cousin will do too.

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