6 min read

What to Look for in a Dissolved Metal Analysis

Thu, Mar. 08, 2018

metal gears

Oil can be high maintenance. It’s not something you just dump in your system and forget about. You have to monitor it, manage it and oversee it. Just letting oil cycle through your system without routinely testing it is a sure ticket to equipment damage.

If you work with oil, you know this. You know that to properly maintain your oil you should be getting routine oil analysis reports that include tests for multiple aspects of your oil. Depending on the type of oil you are having analyzed, these tests can include:

AN (acid number or total acid number)

SAN (strong acid number)

H20 (water content)


ISO (particulate contamination levels)

ISO Code Resistivity (electrical insulating properties of a fluid)

Dissolved Gas Analysis

FTIR Condition Monitoring (Fourier-transform infrared spectroscopy)

Patch Weight

MPC (membrane patch colorimetry)

Spectrographic Analysis

RULER (antioxidant additive levels)


Which part of the report you focus on depends on your specific fluid, the lab measuring it and your needs, but today we’re going to focus on one important part: the Spectrographic Analysis. The Spectrographic Analysis measures the elements associated with contamination, additives, wear and dissolved metals. This part of the report, also known as the Dissolved Metal Analysis, is one we get multiple questions on, like, “What the heck do we do with this?” Keep reading to see why you should give your Dissolved Metal Analysis a closer look and what you should do with the information you find.

Why Dissolved Metal Analysis is Important

Why should you care about this section of your lab report? First, consider your machinery -- it’s likely made of metal. As the machinery runs, the parts move together and, over time, cause wear and tear. Small, undetectable-to-the-human-eye pieces of metal can chip off and fall into your oil, contaminating it.

Additionally, when dissolved metals start accumulating in your oil, they act as catalysts for oil breakdown and can contribute to deposit and gel formation. These formations can then cause valve restrictions and mask your filter elements, causing a less-than-optimal scenario for your machinery and workflow.

Multiple test methods exist for quantifying metals levels in lubricants, but in our experience, we’ve found that the ASTM D5185 is the most accurate report for this purpose.

What Should and Shouldn’t Be in Your Dissolved Metal Analysis

When reading your report, it’s important to first notice that your report measures dissolved metals in PPM (parts per million). Next, your job is to identify what should and what shouldn’t be in your report (i.e., in your oil).

What Should Be in Your Oil

What should be there is the additive package, which helps to improve the performance of your oil. This is the “good” stuff; the specific makeup of the oil is probably the reason you purchased that type of oil in the first place. Check that the additives are consistent with what’s normally found in your oil. If you find that there are changes in the level of additive elements, it can indicate that the lubricant has been mixed with a foreign fluid.

What Shouldn’t Be In Your Oil

Once you’ve established that your oil has what it should, next you need to identify what doesn’t belong in your oil. If you see on your report that high levels of dissolved metals are showing up, it may mean that your equipment is undergoing unusual amounts of wear. This is often an early indicator that your equipment is heading for failure.

Metal entering from machinery is a common internal cause of dissolved metal contamination. However, you may see elements on your report that aren’t from your machinery. These are likely elements that are entering your oil from external sources. Depending on where your plant or site is located, how often your fluids are exposed to air or if you have a pump, valve or seal leak, external contaminants can enter from the surrounding environment.

Even if you get a “pass” rating from your lab, don’t always assume that your oil is perfectly fine. Diving into your lab report to identify the contaminants found in your oil helps you be proactive, monitoring and identifying small issues before they become catastrophes.


Examples of Trouble Spots in a Dissolved Metal Analysis

Let's take a look at two reports that have a dissolved metal analysis in this. In these two excerpts, you'll see highlighted areas where the levels of dissolved metal are higher than expected. 

1. dissolved metal analysis

This report, dealing with a phosphate ester fluid, shows elevated levels of Fe, or Iron. Checking your Fluid Analysis Reference Guide, you'll see that the common causes of Iron in fluid include: bearings, blocks, brake pads, camshaft, cast iron, crankshafts, cylinders, discos, gears, housings, hydraulic pump, vanes, gears, pistons, liners, oil pump, power take-off (PTO), rings, screws or shafts. Most likely, the elevated levels of Iron are due to an internal cause, like pieces of metal breaking off and entering the fluid. 



dissolved metal analysis  

This report, showing analysis of a turbine oil, has elevated levels of Ca, or Calcium. Checking your reference guide, you'll see that causes could be cement dust, Fuller's earth, grease thickener, gypsum, hard water, lignite, hard rock dust, oil additive: detergent, oil additive: rust inhibitor, road dust, rubber, salt water or slag. If this fluid was running inside machinery that was located in a mining site, for example, the Calcium could be coming from an external source: the dirt or dust entering from the environment. 


What to Do with Your Dissolved Metal Findings

By now, you should be able to identify the contaminants that do and don’t belong as well as whether or not they were internally or externally generated. Armed with this data, you can now begin to troubleshoot.

If the contaminant came from within the system, break it down. Was it generated in the machine? If so, where? What components on this machine uses this metal? For example, a common contaminant found is Pb or lead. Consulting your Fluid Analysis Reference Guide, you should be able to see the common sources for lead: Babbitt, Journal Bearing (Overlay), Bronze Alloy, Solder, Balancing Weights, Gasoline Additives, Paint and Road Dust. If you have ball bearings, which are typically made of the alloy Babbitt, you may deduce that your bearings are chipping and flaking, causing the lead contamination.

If it was brought in from the outside, consider it. Was it due to a seal leak? Or did it happen when you were adding more oil? Thinking through this process will help you keep tabs on your machinery while also ensuring your oil is performing at its best.

Armed with Your Results, You Can Take Action

Now that you’ve really thought through the possibilities of where contaminants are coming from and how they entered your system, you're at a wonderful advantage. This is the point where you can have the upper hand against this contaminant. Here's where you get to ask yourself, "What can I do about it?"

Your goal here should be to solve the problem. If you have a hose leak, fix it. If your machine components are breaking off pieces of metal into your oil, it may be time to replace them. The bottom line is this: Do whatever it takes to keep contaminants out of your oil.

We recommend getting a dissolved metal analysis report often, at least every 1-3 months. You may even get it more often if you have frequent recurring issues. Regardless of how often you do the testing, make sure that you keep a close eye on the results. Doing so as you receive the reports can save you a lot of money and headaches down the road by staying on top of issues as they arise, not waiting until they get out of control.

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Written by Jennifer Yeadon


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