Can You Filter Hydraulic Oil Yourself? A Quick Guide

Filtering hydraulic oil yourself is possible, but only when contamination is minor and the right equipment is available. Incorrect DIY filtration can damage the hydraulic system, so understanding when—and how—to do it is essential.

When DIY Hydraulic Oil Filtration Is Acceptable

You can filter hydraulic oil on your own when:

✔ Light Contamination

Slight cloudiness or small particles

No severe oxidation, acidification, or burnt smell

✔ Temporary or Emergency Use

Field work or sudden contamination events

✔ Maintenance Filtration

Routine bypass filtration to extend oil life

✔ Non-Critical Equipment

Avoid DIY filtration for high-precision and critical machines.

How to Filter Hydraulic Oil Yourself (Short Version)

1. Identify Contamination

Check color, clarity, and visible particles

Filter paper test:

Dark center = particles

Diffused ring = water

If oil is black, burnt, or heavily emulsified → ｒｅｐｌａｃｅ oil instead

2. ｓｅｌｅｃｔ Proper Equipment

Particle removal: 3–10 μm filter elements

Moisture removal: coalescing filters or vacuum oil purifiers

Portable carts: OK for maintenance

Never use cloth, stockings, or unprofessional media

3. Perform Filtration

Shut down system and depressurize

Drain oil from tank bottom and pre-filter

Clean sludge in the tank

Refill and run circulation filtration at idle

ｒｅｐｌａｃｅ filter elements when pressure rises

4. Post-Filtration Check

Repeat visual and filter paper tests

For important equipment, send samples for ISO 4406 cleanliness testing

Risks and Limitations of DIY Filtration

Cannot restore oxidized or chemically degraded oil

Risk of introducing new contaminants

Incorrect filter precision may harm precision valves

Removing emulsified water requires special equipment

Improper operation may introduce air into the system

Professional Recommendations

Test hydraulic oil every 2000 hours or annually

Compare cost of new oil vs. filtration vs. downtime

Maintain seals, breathers, and ｒｅｐｌａｃｅ filter elements regularly

Summary

DIY filtration works for lightly contaminated, non-critical systems when proper equipment is used. For precision machinery or severely deteriorated oil, professional filtration or complete oil replacement is the safest and most cost-effective option.