Drinking a glass of dirty water might quench your thirst, but it could also make you sick. The fluid that allows your body to operate needs to be pure. The same goes for the fluid which makes a hydraulic system function — dirty hydraulic fluid can cause your system to break down and fail.

A hydraulic filter removes damaging contaminants from the hydraulic fluid to protect your equipment. FRAM’s P1653A Hydraulic Filter is our top choice for its ability to filter out contaminants down to 10 microns. To learn more about choosing a quality hydraulic filter, keep reading.

Considerations when choosing hydraulic filters

If you are starting from scratch, with no owner’s manual or manufacturer’s recommendation, the most important aspect of purchasing a hydraulic filter is targeting and meeting your cleanliness level. This is done through an ISO (International Standards Organization) code. The code details the level of filtration that is needed for each component in a hydraulic system. The filter you choose should be based on the highest level of filtration needed. In other words, if one component needs to filter out particles down to 22 microns (22 millionths of a meter), while another needs to filter out particles down to 12 microns, you need a hydraulic filter that filters out particles down to 12 microns.

Filter media

The three main types of filter media are cellulose fiber, wire mesh, and fiberglass. Cellulose fiber is inexpensive, but it is also the least-effective material with the shortest lifespan. Wire mesh is the most durable filter material, but it is incapable of filtering out the smallest particles. A fiberglass filter is more durable than cellulose and it can filter out finer particles than wire mesh.

Efficiency rating

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There are three main types of efficiency ratings for hydraulic filters: nominal, absolute, and beta. Since there is no standard set for a nominal rating, this is not the best type of rating to use. It is better to consider an absolute rating, which states the largest size particle that can pass through the filter material, along with the beta rating. The beta rating tests the number of particles on either side of a filter to determine how effective it is.


Temperature is important because oils with a low viscosity index (VI) become thicker in colder temperatures and may require the increased durability of a wire mesh filter. Oils with a higher VI are more consistent in viscosity in colder temperatures, making it safe to use any type of filter media.

Read more: The best hydraulic filter