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Intelligent Lubrication Solutions™

Intelligent Lubrication Solutions™


How to Read an Oil Analysis Report — 3 Key Data Points

Posted by Jeff Muellenbach on May 17, 2016 8:26:00 AM

Reading-Oil-Analysis-Report.jpgIn many of our previous posts, we’ve talked at length about the importance of regular oil analysis and proper sampling techniques. Oil analysis is critical for identifying any trends and problems in your oil and machine, and you can use that information to make important proactive maintenance decisions, such as decreasing unnecessary fluid change outs and scheduling repairs in a timely manner.

That being said, though it’s easy to see the benefits of regularly testing oil samples from your machines, analyzing the results of these tests can be pretty confusing. An analysis can provide you with lots of data about your oil and equipment, but if you do don’t know what data you’re looking for, it’s easy to get lost. To help remove some of the confusion from this process, I’ll summarize the most important data trends.

3 Questions an Oil Analysis Answers 

Before we dive into what exactly you should be looking for though, it’s important to understand the purpose of an oil analysis. Apart from giving you deeper insights about the health of your oil and machine, there are 3 specific questions that every oil analysis answers:

  1. What is the fluid health on the fluids within your equipment?
  2. What is the machine health of your euipment in reference to the lubricated system?
  3. Do you have any issues that are starting to manifiest within your equipment (bearing wear, AF contamination, etc.)?

Why are these questions so important? Because a simple yes or no to each of them will determine whether or not you need to change your oil right away. If your machine components are wearing at a faster than normal rate, for example, you’ll know you need to make immediate adjustments to your oil to reduce wear—in which case an oil analysis can also help clue you in on what to change in order to make those adjustments. For example, your analysis may show that your oil is very dirty and needs to be filtered, or is nearing the end of its useful life.

Case in point: one of our customers started doing engine oil analysis about 3 years ago. After initial tests revealed their oil was being diluted and contaminated by diesel (fuel dilution), they admitted they were able to avoid several engine blow-ups, because they caught and fixed it before it become a major problem. It’s reasons like these that make oil analysis a crucial part of every company’s lubrication maintenance.

The 3 Most Important Data Points on an Oil Analysis Report

Though oil analysis reports provide you with a lot of data and insights about your oil, some data is more useful than others when it comes to telling you whether or not to take action. To help simplify the hundreds of numbers on the report, focus on these 3 areas: viscosity, oxidative life, and metals analysis. These will help you determine if the oil is still in a useful state, wearing at a normal rate, or contaminated.


When talking about engine oils, gear oils, and hydraulic fluids, viscosity is the single most important factor in properly lubricating your equipment. If your oil is too thin, it won’t provide enough protection for your components. If your oil is too thick, however, it’ll make your machines work harder than they need to, increasing energy consumption. In either case, both can lead to more problems with your machines, including oxidation, abnormal wear, or decreased fluid life. Check to make sure your oil’s viscosity is within OEM requirements by referring to the machinery’s manual. In the course of testing, your lab partner will be able to tell you whether the fluid is out of ISO or SAE spec ranges as well.

Oxidative Life

The oxidative life of your oil refers to the acidity and alkalinity in your oil, and is represented on an oil analysis report as the acid number and base number. Acid number testing is used primarily on non-crankcase oils to measure the concentration of acid in your oil, whereas base number testing is used primarily on over-based crankcase oils to measure the reserve of alkalinity in the oil. Too high an acid number can signal oil oxidation, additive depletion, or improper lubricant usage, whereas a low base number might indicate high levels of acid formation from the internal combustion process.

Wear Metals Analysis (a.k.a. Elemental Analysis)

Wear metals analysis is a test designed to measure the concentration of wear metals, contaminants, and additives in your oil. When the gears and components in your machine rub together, microscopic pieces of metal break off and accumulate in your oil over time, as well as other contaminants (both chemical and physical). By measuring the wear metal and contaminant levels in your oil, you can see how healthy your system is and can use the different measurements to determine the cause of the wear or contamination. In fact, here’s a list of different metals and their possible sources from Machinery Lubrication magazine:


After Reviewing Your Report…

Once you’ve reviewed your report and made note of any warning signs in your fluid, the next step you take varies by company, your role, and the depth of your lubrication knowledge. Ideally, your next step involves using the data from the report to make immediate changes to your oil and any associated lubrication procedures in order to correct the problem before it affects your equipment.

If you’re not sure how to interpret the results, or don’t have the knowledge or resources to make the necessary changes, make sure you contact your fluid supplier for help. At U.S. Lubricants, we’ve analyzed thousands upon thousands of oil analysis reports, and we know exactly what to look for and how to fix it. All you have to do is get us a good sample, and we’ll handle all the complicated testing and analysis.

For more information about how U.S. Lubricants can help you with your oil analysis testing, please contact Tony Springer at TSpringer@uslube.com or by phone at (800) 490-4900 ext. 8823.


Topics: Machine Reliability, Oil Analysis