The Many Uses of Hydraulic Oil

Hydraulic oil is a critical component in various industrial and mechanical systems. While its primary purpose is, of course, to transmit power in hydraulic machinery, the versatility of hydraulic oil extends far beyond that. Hydraulic oils are used for many mechanical purposes where high pressure and extreme temperature are critical factors. Whether your hydraulic system is in a car, a lift, a plane, or a cruise ship, there is a magical elixir of mineral oils, glycols, esters, and additives to fit the situation. 

Resource: Oil Sampling Best Practices

Operational Uses


Hydraulic oil plays a crucial role in automotive applications, most notably within the braking system. Brake fluid, a type of hydraulic oil, is responsible for transmitting the force applied to the brake pedal to the brake calipers or drums, ultimately stopping the vehicle. Its unique properties, such as high boiling points and incompressibility, ensure consistent braking performance even under extreme conditions. Your vehicle’s transmission and power steering systems also rely on hydraulic fluid to perform, so it’s safe to say that it is a very important component to keep automobiles of any kind running–and stopping–properly. 

Heavy Machinery

Bulldozers, excavators, cranes, tractors, and lifts, use hydraulic systems to create enough force to move materials and equipment. Many of these systems employ hydraulic cylinders that transfer power through the hydraulic oil between cylinders, often with the assistance of motors. When high-pressure, heavy load conditions are present, a fluid with a higher viscosity grade and anti-wear additives works the best. For plows and applications that operate in extremely cold temperatures, anti-freeze additives are also considered.


Hydraulic oils used in aviation or aerospace applications must fulfill a host of different demands, because they come into contact with a wider range of environments. A high viscosity index, low-temperature properties for high altitudes, and oxidation resistant additives make the oil more reliable for such a demanding industry. Aviation-specific oils are used for flight controls, landing gear, brakes, wing movement, and other aircraft hydraulic motors and pumps.


Boats and ships require hydraulic oils for maneuvering, and these hydraulic applications include steering systems, bow and stern thrusters, anchor windlasses, and shell doors, among others. Hydraulic oils in the marine industry are often biodegradable due to regulations and the fragile environment in which they operate. It is also necessary that these fluids are long-lasting and efficient in cold temperatures.

Resource: Cross Reference Guide For Popular Hydraulic Oils 

What About Restrictions?

Finding hydraulic oil that meets both fire safety and environmental concerns is important. 


To address fire safety, it's essential to select hydraulic oils with high flash points and low flammability characteristics. Non-mineral oil hydraulic fluids, especially water-glycol or phosphate ester synthetics, are suitable for moderate operations where it is dangerous to generate too much heat. Military and metal industry applications, die-casting machines, and furnace hydraulic systems commonly use these oils to reduce fire risks.

Environmental Friendliness

In addition to the maritime industry, biodegradable oils are used in off-shore drilling, forestry, and other applications where leakage can damage or disrupt the nearby ecosystem. These hydraulic fluids are made from vegetable oil, synthetic esters, and poly glycols. Vegetable and animal oils are nontoxic but can be less effective and oxidize more easily to their non-water-soluble counterparts

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