Why starting with clean oil is a maintenance must
Equipment health is a moving target. You can follow every preventive maintenance schedule, track every fluid change, and still face unexpected downtime. What’s often overlooked? The contaminants you can’t see: microscopic particles hiding in the oil you just added.
Modern engines and hydraulic systems are more sensitive than ever. They’re built with tighter tolerances, greater efficiency, and more complexity. But that also means they’re more vulnerable to tiny threats, like particles under 10 microns, that can slip through filters and quietly damage your most critical components. The hard truth is that if we assume fresh oil is clean oil, it leaves equipment vulnerable to harsh wear and tear.
The invisible enemies in your oil
According to research from Noria Corporation, 82% of mechanical wear is caused by particle contamination. The most damaging particles are clearance size small enough to enter the tiny gaps between moving parts, but large enough to scratch, pit, or fatigue those surfaces.
For comparison, a human hair is about 60 microns wide, and a typical clearance size particle causing wear might be just 5–10 microns. At that size, a single grain of sand can act like a cutting tool inside your components.
These particles can come from anywhere: dust and debris in the air, moisture from condensation, and even wear metals shed from other parts of the system. Once in circulation, they not only accelerate equipment degradation, but they also deplete additive packages in the oil, reducing its protective properties.
Contaminants this small can’t be seen, but they can be measured. This is where the ISO Cleanliness Code becomes essential. It quantifies the number of particles in three size ranges (4 microns, 6 microns, and 14 microns or larger) per milliliter of oil. For example, a cleanliness rating of 16/14/12 indicates specific maximum particle counts for each size threshold. Many OEMs require oil to meet or exceed these levels to protect sensitive components and ensure equipment longevity.
Why “new” oil might not be clean
Here’s the kicker: most new oil isn’t clean enough to prevent damage.
During a typical journey from refinery to end use, bulk oil can be transferred up to eight times from storage tanks to trucks to drums to dispensing equipment. Each step introduces opportunities for contamination. Studies have shown that typical new oil can contain up to 32 times more particles than what’s acceptable for sensitive equipment.
One striking example: just one teaspoon of dirt in a 55-gallon drum can introduce roughly a billion particles 4 microns and larger. That’s enough to push even fresh oil beyond safe cleanliness levels, especially for high-performance fleets using modern, tightly engineered components.
It’s a common misconception to equate oil performance specifications (like viscosity or API ratings) with cleanliness. But even oil that meets PC-11 or PC-12 engine performance specs may not meet the ISO cleanliness codes required for safe operation.
The limits of filtration
You may often rely on equipment-mounted filters to catch contaminants, but this approach has limitations. Filters are critical, but they aren’t catch-all solutions.
Why? Because the most harmful particles may already do damage before they’re trapped. Additionally, many systems feature bypass valves that allow oil to flow around the filter once it’s reached capacity, ensuring lubrication continues, but at the cost of contamination control.
Worse yet, relying on filtration to “clean up” dirty oil puts unnecessary strain on the system, shortens filter life, and increases maintenance frequency. It’s an uphill battle that could be avoided by simply starting with cleaner oil in the first place. In systems where even small levels of contamination can lead to premature failure, such as hydraulics, transmissions, or aftertreatment devices, these steps are becoming industry best practices.
The payoff of certified clean oil
So, what’s the upside to starting clean?
Plenty. Studies using Noria’s Life Extension Chart show that improving oil cleanliness from 20/18/15 to 17/15/12 can double the life of hydraulic system components. In fleet operations, that translates directly into reduced maintenance costs, fewer unplanned breakdowns, and extended equipment life.
Certified clean oils are tested and documented to meet specific ISO cleanliness codes at the point of delivery. This ensures fleets aren’t inadvertently introducing damaging contaminants the moment they fill a tank or reservoir.
It’s the maintenance equivalent of a clean slate.
A cleaner start means a longer life
For today’s fleets, uptime is everything. Preventing avoidable wear, avoiding premature component failures, and reducing total cost of ownership all begin with lubricant management. And while it may be tempting to rely solely on filters and assume new oil is clean, the data tells a different story. Contamination starts earlier than most people think, and it’s far more damaging than most people see.
That’s why leading maintenance teams are rethinking their approach. They’re not just checking performance specs. They’re checking cleanliness specs. They’re not just monitoring oil condition during operation. They’re starting clean, and staying that way.
Because what you can’t see can absolutely hurt your fleet.
About the Author
Max Cundiff
Industrial Sector Manager, Chevron
Max Cundiff is the Industrial Sector Manager at Chevron, where he brings more than a decade of experience within the oil and gas industry. With a background spanning customer relationship management, international business, and strategic growth initiatives, he is dedicated to helping customers improve performance while advancing Chevron’s industrial market presence. Max holds both a BS in Business Administration and an MBA with an emphasis in Entrepreneurship from the University of Louisville.