Used Oil Analysis

Oil analysis is an effective tool that can help you monitor the condition of your engine,” says Dan Arcy, OEM technical manager, Shell Lubricants. “The knowledge gained from a consistent oil analysis program can assist you in optimizing your oil drain...


Oil analysis serves as an early warning system that can alert a maintenance operation to problems before they become costly headaches, says Shell Lubricants’ Arcy. “Used-oil samples can tell if contaminants – such as water, coolant, fuel or dirt – are getting into the oil, indicating a head gasket leak, a leaking fuel injector or other problems.

“Spectrochemical analysis detects the presence of wear metals in the oil. Unusually high amounts of wear metals could be a sign of abnormal wear.”

Spectrochemical analysis is an analytical technique in which an oil sample is heated to a high temperature, usually in a carbon arc, to produce emission lines whose intensities are proportional to the abundance of elements present.

Typically with spectrochemical analysis, using computerized test equipment, a very small amount of used oil sample is energized (burned in an electric arc), explains Jeff Wohlwend with OilCheckUp, a custom manufacturer and worldwide distributor of filtration test media and multi-fluid test strips. This results in a wavelength, or color, of light that is compared against the standard acceptable levels of wear metals or contaminants. These results reflect the concentration of all dissolved wear metals, both from the component and the fluid.

This lab analysis provides a quantitative evaluation of a fluid’s composition and condition, including viscosity, total sludge content, particle count, glycol contamination, fuel dilution, fuel-soot level, grime and additive package depletion, adds Ron McElroy, president and chief technology officer of Fluid Rx, a company that does instant lubricant diagnostics.

Both Arcy and Citgo Lubricants’ Betner note that more specialized tests can be performed on an oil sample. There are oil analysis services that offer upgrades or additional testing depending on the application, operating conditions and maintenance goals, says Betner. Additional tests, or premium used oil analysis, can help in determining the optimum oil drain intervals or identify specific problems, Arcy adds.


When taking an oil sample, Arcy of Shell Lubricants advises taking a sample in the same manner each time, as this keep the results consistent. “Withdrawing oil through the dipstick opening is a good way to take the sample. This can reduce the chance of outside dirt or contaminants getting into the sample.”

All paperwork that accompanies each sample needs to be as complete as possible, says Betner of Citgo Lubricants. This information is critical to providing a complete and accurate analysis report.

Be sure to note if any oil was added between oil drains and what type was used, Arcy says.

Once a lab receives an oil sample, it typically takes 24 to 72 hours before the data is ready for reporting.

“It is very important the oil analysis user realizes that the longer it takes to get the sample to the lab the longer it takes to get data back,” Betner stresses. “It is not uncommon for samples to sit around shops waiting to accumulate several samples so that a bundle can be shipped to save on shipping costs. But in the long run, the value of the testing is lost due to this type of delay.”


When the oil analysis is received, it is necessary that the report be fully understood, says Citgo Lubricants’ Betner. Consult with the oil analysis provider if unsure of anything.

“Newer engines tend to have some anomalies that can produce false critical reports,” he says. “Knowing when and why these situations occur can avoid loss of confidence in the reporting, and more importantly, when and how to react to the data.

“Generally, oil contamination is the number one cause of lubrication-related failures, so critical reports involving coolant, dirt, fuel and in some cases, soot contamination, should get the full attention of the user.”

If the sample indicated a critical issue, the customer is contacted by phone or fax by the laboratory, communicating the sample result, Shell Lubricants’ Arcy says.

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