Oil Analysis

Condition-monitoring technique · Updated 2026-07-15

Oil analysis examines a lubricant sample for wear metals, contamination and degradation, revealing the condition of gearboxes, bearings and compressors. Like a blood test for machinery, it catches developing wear and lubrication problems before they cause failure.

How it works

A sample of the lubricant is tested for wear-metal particles (iron, copper, chromium), contaminants (water, dirt, fuel) and the oil's own condition (viscosity, additives, oxidation). Rising wear metals point to a specific component degrading; contamination explains why; oil degradation flags when the lubricant itself must be changed. Combined with vibration, it pinpoints both the failing part and the root cause.

What the data shows

Rising iron indicates gear or shaft wear; copper points to bearing or bushing wear; water or coolant ingress accelerates failure; falling viscosity or additive depletion means the oil can no longer protect the parts.

Oil Analysis in practice

Oil Analysis is versatile because it works across many asset types: gearboxes, compressors, bearings and others. This breadth is both a strength and a consideration — a wide-ranging technique often requires less customization, but may not be as specialized as a dedicated point-solution. Most plants use Oil Analysis in combination with other techniques to build a complete condition-monitoring programme.

In practice: Oil Analysis excels at catching developing faults early, when they show as subtle changes in the monitored signal. The challenge is distinguishing a real fault signal from noise. Successful Oil Analysis programmes typically combine threshold alarms (alert if the signal exceeds a limit) with trending analysis (alert if the signal is rising fast, even if still below the limit). Both approaches matter for reliability.

Getting started: Implement Oil Analysis on your most critical assets first — those whose failure causes the longest downtime or highest cost. Start with one or two assets to learn the signals on your equipment and processes, then expand. Many plants find that Oil Analysis baseline data (what 'normal' looks like) takes 2–4 weeks to establish, after which the technique pays for itself through early fault detection.

Oil Analysis by equipment

Glossary: Oil Analysis →