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Oil Viscosity - Striving for Perfect Measurement Accuracy

Always improving accuracy and repeatability of oil viscosity results

Happy New Year, MRT blog readers!

I'm kicking off the new year emphasizing how much effort we put into providing the most accurate test results as possible. At the top of the list of importance is oil viscosity. In Q3 2021 we validated and began using one of our favorite lab instruments, the Cannon CAV 4.1 Kinematic viscometer.

Automated Viscometers and Rheometers | Accurate Viscosity Measurements | CANNON Instrument

In our opinion it is the Formula 1 race car of automatic viscometers - a finely tuned machine supported by an excellent pit crew of Cannon service technicians. We look forward to purchasing more of these. The instrument is extremely consistent, and last week a customer pointed this out by analyzing their MRT viscosity results on a certain gearbox lubricant over the past several years.

I'm referring to the attached image of the viscosity results of an ISO VG 320 gear lubricant since January 2019. Notice that all of these viscosity results are less than 10% above or below the rated viscosity of 320 Centistokes for this oil; therefore, all of the results are NORMAL viscosity readings. This is great news, but notice the spread of the results to the left of the dotted red line compared to the right of the dotted red line. Why is there so much more variation in the results before Q3 2021? This was the question from our customer. My first reaction was that this customer probably had a seal leak issue in the past that was fixed in late 2021, and there was no longer a process contamination issue in the gearbox. But then I looked more closely at the small range on the y-axis of the graph. All of these results are very normal throughout the period, but after Q3 2021 the range is significantly tighter with results that are much more consistent on a month-by-month basis. A process contamination issue typically would create a much wider range of viscosity results over time. Also, it's more likely that all of the viscosity results would have been less than 320 cSt due to contamination, and not above and below 320 cSt.

We looked back to when the Cannon CAV 4.1 viscosity was put into service and realized that because of this instrument and our uniform application of our laboratory procedure, these results became much more consistent and accurate. It's great to have normal oil analysis test results, but we take pride in always improving our instrumentation and our procedures.

Tue Jan 02 2024, by Ben Hartman, CLS
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