Hydraulic oil is an incompressible fluid used to transmit power in hydraulic machinery and equipment. Hydraulic oil, also known as hydraulic fluid, can be synthetic or mineral based. Although this useful fluid is commonly used for power transmission, hydraulic fluid can also act as a sealant, coolant, and lubricant within machinery and equipment. Most oils manufactured are either mineral-based or synthetic. Mineral-based hydraulic oils are derived from crude oil fractions, while synthetic hydraulic oils are made from chemically produced base fluids.

The key role of hydraulic oil in a hydraulic system is to transfer power from one end of that system to the other and to the various hydraulic components. When an external force is applied to the incompressible hydraulic fluid, usually from a piston within a cylinder, the oil is pushed through the hydraulic system, ultimately creating a force on another part of the system. This results in a movement or action. Usually, applying force to a material results in compression. You may therefore be wondering whether hydraulic oil is compressible, but a fundamental property of hydraulic fluids is that they are incompressible.

Hydraulic fluids are used in many applications in every industry. To give you an idea of the wide variety of uses for hydraulic fluid and why industrial hydraulic oil is so important, here are 10 examples of equipment and machinery that use hydraulic oil. Forklifts – The hydraulic system in forklifts and stackers is important to power the incredibly powerful forks that must lift some super heavy loads.
Log Splitters – The ramming mechanism in a hydraulic oil log splitter requires hydraulic fluid inside to provide the immense power that can split logs with ease. Auto Lifts – Auto lifts (jacks, car lifts, etc.) use hydraulic jack oil to help with their impressive power range. Snow Plows – Hydraulic oil for a snow plow and snow removal equipment is essential for the powerful operation of the hydraulic lifting, tilting and angling movements of the snow plow blade. Skid Steer Loaders – Skid steer hydraulic oil is as versatile as the machine it works with. Hydraulic oil plays a major role in the many tasks that this machine can competently perform. Aircraft (Aviation) – In the aviation industry, it is essential that aircraft hydraulic oil is reliable as it is used in aircraft control systems, aircraft hangar doors, aircraft jacks and aircraft controls. Aircraft – Aircraft and air compressors require high performance hydraulic oils with anti-wear additives for protection. Tractors – Tractor hydraulic oil is essential for the operation of hydraulic brakes and hydraulic systems in agricultural vehicles and equipment. Cruise Ships and Marine Industry – Many marine vessels use hydraulic oil for stabilizers. Stabilizers reduce the amount of rolling that can affect the stability of the ship and cause motion sickness. This is just one of many other applications that require hydraulic oil in marine vessels.

Depending on how you use your hydraulic fluid, there will be additional additives to help it perform under different conditions.
The different hydraulic fluid additives can be listed as follows. Antiwear – helps extend the life of equipment and machinery. Cold Flow – additives that allow use in extremely cold weather conditions. Anti-foam – an anti-foam agent for hydraulic oil reduces the foaming in the fluid that can be caused by detergents. This foaming can cause damage and reduce the lubricity of the product. Antioxidant – Reduces sludge buildup and allows longer use without oil changes. Rust inhibitor – Forms a protective coating that reduces the risk of rust damage caused by contact with oxygen. These additives are used alone and in combination in various blends designed for different purposes. Hydraulic oil properties can vary depending on the additives used, but typical properties tend to be high viscosity index and incompressibility.