This in-depth guide will teach you how to understand oil analysis results. Gain insights on oil condition, contaminants, wear metals, and additives to maintain machinery performance.

Oil analysis is a crucial part of machinery maintenance. It provide insights into the condition of the oil, the health of the machinery, and the presence of contaminants. Interpreting an oil analysis report correctly is essential for maintaining optimal machinery performance and preventing costly breakdowns. This guide from Machinery Lubrication breaks down the four key elements of interpreting an oil analysis report, providing a clear and concise approach to understanding these critical diagnostics.

To understand this, we will be siting a real life scenario that gives you a deeper insight on why it is important to understand and interpret oil analysis reports. 

A Caterpillar gas engine client was not pleased to find a significant concentration of copper in his lubricant sample, even though the engine had less than 2,000 total hours and less than 2,000 running hours. After receiving the second report, the client became furious and decided to stop the engine, dismount it, and check the bearings. Despite his efforts, there were no issues found. This led to a serious consequences such as loss of productivity, manpower waste, and a higher injury risk on their plant facility.

The customer was informed that a red oil analysis report may be an early indicator of engine problems, but it doesn’t necessarily mean that opening the engine is not always essential. It is important to understand all the parameters. Due to the client’s lack of training, he assumed that their machine was fine since there’s a low probability of wear because of its age. This led to an incorrect call and unnecessary shutdown, with no evidence of wear material in the engine or bearings.

This article highlights various areas of ignorance about understanding and reading oil analysis report. The advantages of oil analysis program will be wasted if these misconceptions are not corrected, costing time and money.

Oil analysis report interpretation is a science. Engineers and technicians must be trained to properly understand and take into account all of the parameters. This will help in precisely evaluating:

• Wear metals and the machine's overall condition.
• The condition of the lubricating system (contamination).
• The condition of the grease.

 Here are the four elements that you need to understand in order to interpret oil analysis report.

1. The PPM Scale 

In lubricants, the amount of wear metals and additives are measured in parts per million (ppm), which is equivalent to milligrams per liter (mg/L). The density of chemical element varies, with one ppm being equal to a million time absolute fractional amount.

To properly understand ppm, imagine yourself completely mixing four drops of ink into a 55-gallon bucket of water. This process will produce ink concentration of 1 ppm. Other comparison that could help in understanding the scope associated with one ppm are as follows:

• One millimeter in one kilometer.
• One minute in two years.
• One second in 11.5 days.

A concentration of one ppm in lubricant corresponds to 0.0115 cm3 of copper. This is roughly around 4 microns thick on a bearing of a 37-liter oil sump engine. However, this is incorrect because the engine has several bearings and other copper sources.

The question now is, can we see wear at a thickness of 4 microns with our naked eyes?

Our vision extends to about 40 microns, so the answer is no. In summary, the average person would not notice a 100 ppm concentration brought on by wearing metal.

2. Elemental Analysis 

For elemental analysis, two different techniques are employed: the Rotating Disk Emission (RDE) Spectrometer (ASTM D 6595) and the Inductively Coupled Plasma (ICP) Spectrometer (ASTM D-5185). Both devices stimulate the atoms in a sample using a high-energy source.

The atoms produce light energy when their energy is lowered since they do not wish to be in this excited state. Every atom has a unique light energy that is released. As a result, the concentration of each element under test can be determined from the amount of light energy.

The RDE has the ability to evaporate particles as small as 10 um, while the ICP, depending on sample preparation, can evaporate particles as small as 5 um.

Wear metal sizes are all less than 40 microns.

3. Sources of Copper

An oil analysis report's source of copper is not restricted to bearings.  We would have also had additional materials, like tin or lead, if it originated from the bearing, as the bearing's surface was made of alloy. In reality, all other elements were present at normal levels, and the report only noted a high quantity of copper.

On the other hand, a well-established chemical procedure for producing high copper concentrations is colder core leaching.

Copper sulfides occur on copper cooler tubes when zinc dialkyldithiophosphate reacts at an active reaction site in new engines with fewer than 1,500 hours of power. Over 300 parts per million of copper are added to the oil as a result of these sulfides, which eventually evaporate. After the cooler achieves equilibrium, this concentration will return to normal.

4. Wear Metal Levels Can Stabilize 

The purpose of the second oil analysis report for this customer was to verify the results of the first. Only a top-off with new oil would reduce the concentration of wear components in the engine. Since the customer acknowledge that there was no top-off performed, an increase in wear material was anticipated. However, this wasn’t the case.

The concentration difference between the first and second samples was insignificant, suggesting that copper production was reaching a stabilization point. This confirmed that the engine's cooler core leaching occurrence was the cause of the issue.

Though ignorance can be dangerous and cause frustration and lower productivity, great leaders frequently claim that education is expensive. In order for businesses to fully benefit from a high-quality program, it is important that all parties involved in the oil analysis process have the necessary training and certification.

To gain deeper insights and professional skills in oil analysis, consider joining in our Oil Analysis Certification Training. This training program is designed to equip you with the knowledge and expertise to interpret oil analysis reports confidently and effectively. This comprehensive program covers:

• Understanding oil analysis fundamentals
• Identifying oil conditions and contaminants
• Recognizing wear metals and their implications
• Evaluating additive levels and oil health
• Hands-on practice with real-world oil analysis data

At CRE Philippines, we are committed to helping you maintain optimal machinery performance through our comprehensive training programs. Trust us to provide the expertise and support you need to excel in machinery lubrication and oil analysis. Contact us today for you achieve excellence in machinery maintenance and reliability.

You can also check out our previous articles to understand more about oil analysis.

The Significance of Oil Analysis and Particle Counting

Oil Analysis: Key Questions for Comprehensive Insights

Oil Analysis for Optimal Machine Performance: Selecting the Right Tests