Effective Oil Analysis

April 21, 2017

Oil sampling and analysis as a condition monitoring program has been around for many years as part of operating and maintaining heavy mining equipment. The program and photos cited in this case study were from an open-cut coal mine that kicked off their oil sampling program in the 70’s. However, after some time this site reflected on the experiences of theirs and other mines. They began to realise they did not initially achieve the benefits of improved equipment reliability that were desired from the program. It took 10 years before they got it right and it required them to ask themselves, are we getting value from this program?

Site experience:

When asked about their oil sampling program, this is the feedback from the mine for how the program ran in the first 10 years.

  • Samples were taken but the results were not trusted by the tradesperson
  • It was seen as an unnecessary task – wasting time and money
  • Sample results were not understood
  • The wrong sample techniques were used
  • Components were stripped on the basis of the oil sample results and no defects were found
  • Lots of samples were taken that were of no value, lots of money wasted
  • There were still too many unexpected equipment failures
  • Management started to question the Return On Investment

The program turn-around:

When the site realised the program wasn’t effective they implemented an improvement program. The program included the following.

The supervisors were engaged first so they understood what the program was meant to do and how it was going to happen. As part of this program, supervisors were sent to the lab to understand the oil analysing procedures and factors that can influence interpretations.

Tradespeople were formally trained to enable them to understand the results. A simple “Understanding of Oil Analysis” awareness training was started.  It was developed and delivered in-house with the only cost being the trades person’s time.

One key element of the training was the concept of contaminated oil hiding impending failures, which was explained as part of the training. This is where the oil in the equipment is not clean enough to allow the early increases in wear metal in the sample to be visible during the oil analysis process. The excess contamination, that has been left over from historical wear, creates a high level of “background noise” in the measurement of the wear metals. This elevates the “normal” wear metal levels above the levels you would see in an early onset of a failure so the early onset of failure is hidden until the failure has progressed closer to its ultimate failure point. This concept is represented in the graphic below and can apply to any of the wear elements used to identify failures.

Effective Oil Analysis


The graphic shows that good signal detection range (early failure detection) is achieved when the oil contamination is low at ISO -/13/10. If the oil contamination is high at say ISO -/19/16 then the time to failure from detection will be much less.

Led by the supervisors the tradespersons took ownership of the process and its outcomes.

  • Taking clean representative samples in a repeatable fashion
  • Marking samples correctly with the required information
  • Understanding the results of the oil analysis
  • Troubleshooting on the basis of the data and taking appropriate actions.

To aid the interpretation of the oil analysis, the lab was asked to provide trends of the last five sample interpretations on one report which gave more insight to the analysis. It also highlighted where samples were missing or not taken correctly.

How to get the sampling program right first time:

  • Decide if there is a need for an oil analysis program and what are the critical areas to monitor, maybe not all compartments are required (See the previous article)
  • Ensure that oil is being added to your equipment at the right time, to the right cleanliness
  • Compare your equipment performance against others and ask yourself, “Do I need to extend oil and component lives?
  • Select the right people to set the example, attention to detail including cleanliness is the key
  • Provide training in what is expected
  • Set up clear guidelines of what is expected, use lots of photos and images to make it simple to understand and provide simple visual measures of how the program is going
  • Set up target contamination levels, define what optimum results are and recommend cleanliness targets including the monitoring of contractor delivered oil and oil stored in the mines bulk tanks

Monitoring the Program:

  • All results from the outside laboratory are scrutinised – even “non-actionable” results
  • Regular meetings are held with the laboratory to address any issues or improvements
  • Repetitive equipment and sampling problems are identified. It has highlighted where it was difficult to obtain a proper sample.
  • Shortcomings in training have been highlighted
  • Reports with outstanding issues are monitored weekly
  • A monthly management summary report is sent from the laboratory including equipment outside of cleanliness specifications.

The benefits of the program:

These are the benefits stated by the mine now that the program is working for them.

  • Problems are detected early so minor problems were repaired before they became major failures.
  • The “positive” as well as “negative” samples are monitored so money is not wasted on early oil changes or by repairing components needlessly
  • Repair time was shortened
  • Repair events became scheduled downtime to fit into the workload
  • Monitoring the fleet oil analyses helps with fleet management by assessing whether equipment with increasing wear trends will last until other equipment can be made available
  • It has increased the confidence level in equipment reaching or exceeding its component life
  • Developing a complete profile and history of each piece of equipment helps with evaluating equipment performance or planning replacement purchases