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Additives for hydraulic fluids

Hydraulic fluids play a pivotal role in the smooth operation of a well-balanced and well-designed hydraulic system. Their primary function is to convey power, however a hydraulic fluid can also be vital for efficient heat transfer, lubrication and corrosion prevention. We have developed an industry-leading range of ester base fluids which provide outstanding performance benefits to hydraulic fluid formulations. 

Hydraulic fluids based on mineral oil have been widely used due to the inherent lubricating properties and its ability to be used at elevated temperatures. However, there is now an increasing awareness of the impact of large amounts of lubricants entering the environment from hydraulic machinery and there is a strong movement to minimise the impact of human activity on the global environment using renewable and sustainable technologies.

Our products have been designed for environmentally sensitive areas, are made using sustainable and renewable raw materials, and all are ultimately biodegradable and have low toxicity towards aquatic organisms.

Esters for use in hydraulic fluids

Esters are predominantly used as base fluids in the formulation of environmentally acceptable hydraulic lubricants due to their biodegradability and low aquatic toxicity. They can be considered to fall into one of three categories:

  • Natural oils and fats
  • Petrochemical esters
  • Synthetic oleochemical esters.

Synthetic esters derived from oleochemical raw materials are the most versatile of the three categories of esters and generally result from the reaction of a petrochemical alcohol with one or more oleochemical derived fatty acids. They typically have a renewability content of between 70% and 95%. Oleochemical based esters offer a very broad technology platform and enable the design  of biodegradable chemistries with viscosities ranging from approximately 10cSt up to 1000cSt at 40ºC. Importantly, synthetic esters are not classified as dangerous for the environment, nor are they classified as harmful to aquatic organisms.

We have a large range of ingredients available for use in hydraulic fluid formulations under the Crodamol™ and Priolube™ brand names. The range comprises unsaturated, fully saturated and complex esters which all give rise to differing viscosities and properties such as oxidation stability. There is a solution for all types of formulation. 


Explore our speciality ester base fluid additives, made from sustainable, renewable raw materials, for hydraulic fluid applications in environmentally sensitive areas below.

Brochure: Formulating European Ecolabel compliant hydraulic fluids

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Fire resistant hydraulic fluids

Ensure smooth hydraulic operation with fire resistant additives, classified according to the chemical composition to assist formulation.

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Formulating for European Ecolabel?

We can help you select components for Ecolabel compliant hydraulic fluids

The EU Ecolabel for lubricants standard promotes the development and use of lubricating products with reduced environmental impact and many of Croda’s esters for hydraulic fluids are Ecolabel-approved.
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Recommended products

Priolube™ 3970

Priolube 3970 is a low viscosity, oxidatively stable, low deposit forming polyol ester. Priolube 3970 is a high performing lubricant and as it is a polyol ester it therefore has excellent oxidative stability and wear performance.

Priolube™ 2089

Priolube 2089 is a readily biodegradable ester with excellent demulsification and outstanding low flow properties.

Priolube™ 1973

Priolube 1973 is an ISO 46, oxidatively stable, biodegradable and hydrolytically stable ester, suitable for use in a wide range of automotive and industrial applications.

Priolube™ 2065

ISO 46, readily biodegradable and hydrolytically stable polyol ester. It is also an NSF registered HX-1 ingredient and features on the LuSC list.

Priolube™ 3987

Priolube 3987 is an ISO 150 oxidatively stable, biodegradable and hydrolytically stable ester, suitable for use in a wide range of automotive and industrial applications. It is also OSPAR Compliant and featured on the LuSC list.

Priolube™ 2088

An ISO 320, oxidatively stable, biodegradable and hydrolytically stable complex ester, suitable as a base fluid or thickener, particularly in environmentally acceptable lubricants.

Priolube™ 1851

Oxidatively stable, ISO 460 biodegradable complex ester, suitable for use as a base fluid and thickener in a wide range of applications. It is also effective as an additive to improve lubrication properties and features on the LuSC list.

Priolube™ 1847

ISO 1000, oxidatively stable, biodegradable and hydrolytically stable complex ester, suitable thickener and additive to improve lubrication performance in many applications. It also features on the LuSC list.

How can we help you with your application needs?