About KLEENOIL

50 Years of Leadership in Cellulose Depth Filtration

Since 1976, KLEENOIL has specialised exclusively in cellulose depth filtration, delivering trusted oil filtration solutions across the UK and worldwide. Our systems are used across every industrial and commercial sector—from transport and power generation to marine and hydraulic systems—ensuring cleaner oil, longer equipment life, and better machine hygiene.

Our Origin Story

KLEENOIL was established following the Israeli-Egyptian war of 1974, during a time of heightened global awareness around oil conservation. Originally developed to extend oil life in the transport sector, the system quickly proved effective across a wide range of applications.

By 1986, after a decade of success in the domestic UK market, KLEENOIL began exporting—and has since grown to serve over 20 countries worldwide, directly supplying systems for vehicle engines, generators, marine vessels, and increasingly, hydraulic oil purification.

The KLEENOIL Difference

For over 50 years, KLEENOIL has been a market leader in bypass cellulose depth filtration, offering a full-service solution: from in-house design and manufacturing to installation, support, and condition monitoring ; All based in the U.K – ‘MADE IN BRITAIN’.

We provide genuine KLEENOIL filtration products, exclusively based on natural cellulose depth, post production recycled media, to meet the highest standards of oil cleanliness and moisture control.

What Is Bypass Cellulose Depth Filtration?

Bypass filtration—also commonly known as kidney-loop or polishing filtration—is designed to operate alongside a system’s primary filter, continuously drawing off a small volume of oil and passing it through a dense, highly absorbent media at low speed.

Why It’s Better than Full-Flow Filtration

Full-flow filters must handle 100% of the oil flow in real time, meaning the fluid passes quickly through the filter media. Fine particles are often pushed through, and when the media becomes saturated, it may bypass altogether—rendering the system ineffective.
Bypass filters, in contrast, take only a partial flow, allowing for slow, thorough filtration. KLEENOIL filters can remove particles down to 3 microns and absorb 99.5% of water, dramatically increasing oil cleanliness and equipment reliability.
Achieves ISO cleanliness levels better than ISO 18/16/13, matching or exceeding the quality of new oil

How It Works

KLEENOIL systems return highly cleansed oil back to the reservoir in a continuous loop. Over time, this multi-pass process ensures the entire system reaches—and maintains—ISO cleanliness levels better than that of new oil.

Why Cellulose Depth Filtration?

Unlike surface filters, KLEENOIL’s natural cellulose depth media traps contaminants throughout the entire filter structure, not just on the surface. This gives:

The filter’s tortuous internal pathways trap solid particles and absorb water efficiently, making it the ideal long-term solution for critical equipment where reliability and oil hygiene are paramount.

Clean Diesel Matters More Than Ever

With modern diesel engines operating at higher pressures and tighter tolerances, the need for clean, contaminant-free fuel has never been greater. Water and fine particulate contamination in diesel can lead to injector failure, poor combustion, fuel degradation, and costly downtime.

The KLEENOIL filtration technique—branded as KLEENFUEL when applied to diesel—surpasses conventional fuel polishing systems by combining fine depth filtration with powerful water absorption. This ensures fuel cleanliness down to 3 microns and removes virtually all free and emulsified water, delivering ISO fuel cleanliness levels that exceed OEM standards. The result is cleaner combustion, enhanced engine efficiency, and longer component life, even in off-road or remote applications where fuel quality is often compromised.

Proven Over Time – Still Unrivalled Today

While KLEENOIL stands as one of the longest-established oil filtration technologies in the industry, its enduring simplicity and effectiveness remain unmatched. In an age of complex systems and digital add-ons, the core KLEENOIL principle—slow-flow, depth-based bypass filtration—continues to outperform even the newest entrants to the market.

Its robust, maintenance-friendly design, combined with exceptional contaminant and water removal capabilities, offers a level of reliability and value that modern alternatives often fail to match. Decades on, KLEENOIL remains the gold standard for oil cleanliness, trusted by industries worldwide for its consistency, efficiency, and results-driven performance.