Machinery requires constant maintenance and repair to prevent further wearing of machinery or the eventual meltdown of the whole system crash. Oil lubricants are equally as important and require frequent monitoring so as to rule out any anomaly like contamination, degradation or even machinery wear. An oil condition monitoring system operates in-line, on-line or off-line.

In-line monitoring is efficient for real time oil analysis where by all the oil is analyzed as it flows within the system and immediate results are given without any outside influence. On-line monitoring is carried out by testing a sample of the oil in a portion of the system which gives direct results and does not affect the flow of the system. Off-line monitoring involves analyzing a sample of the oil away from the machinery. This type of monitoring exposes the oil to new agents, interfering with the final results.