To me, the answer to this question is sweepingly simple. Lubricants are formulated by humans. They are blended by humans. They are inspected by humans. They are transported and packaged by humans.
They are labeled and stored by humans. When it comes to humans, there is one inalterable constant - we make mistakes. Sometimes this is due to lack of vigilance. Sometimes it’s lack of knowledge. It might even be because of indifference.
Case in point: in 2001, the American Petroleum Institute (API) audited 562 motor oils that were licensed to bear the API marks - approximately one-third of its licensees (83 percent originating from the United States). The tests were performed to determine compliance with API performance standards. This is what the audit reported:
- 4 percent of the motor oils were classified as having significant deviations (one out of every 25 oils tested). Many had the wrong concentration of additives while others failed to meet low-temperature specifications.
- 16 percent were classified as having marginal deviations (one out of every six oils tested).
I view new lubricant quality as a collaborative process - like teamwork. While lubricant suppliers, distributors and transport companies bear the brunt of the responsibility, users influence quality as well. For instance, when users foster a cavalier attitude about the importance of lubrication in general, efforts made to improve lubricant quality go unnoticed and certainly unappreciated.
Perhaps users underestimate the degree of risk associated with poor lubricant quality. Some users may even fear being perceived as distrustful if they question quality. In my mind, this is muddled thinking.
We at Noria want to do everything possible to bolster and support excellence in lubrication - for suppliers and users alike. On one hand, we don’t want to raise unwarranted alarm. On the other hand, we don’t want to live in a state of denial by saying everything is fine, don’t worry.
I’ve served on numerous failure investigations in recent years in which defective lubricants contributed to expensive and unfortunate repairs and downtime. These were regrettable situations. They were also the exceptions, not the norm. And fortunately today, used oil analysis frequently catches many problems before serious failures develop.
However for certain machines, deviations in lubricant quality can lead to disastrous consequences. This punctuates the need to confirm the quality of new lubricant deliveries, especially when the need for reliability is particularly important. Likewise, a quality-minded lubricant supplier will appreciate receiving feedback, both good and bad, from users who run such tests.
Let’s take a look at how deviations in new lubricant quality can occur:
Formulation Error
Changes to lubricant formulations are sometimes made on the run, that is, without advanced performance testing by the additive supplier or formulator. This can contribute to additives that clash in service or simply fail to properly dissolve in the base oil. The risk is greatest for blend-to-order jobs or when formulations have been modified in a rush to solve a particular problem.
Blending Error
Blending a lubricant is a lot like making soup. You prepare a confection of essential ingredients. For a lubricant, these ingredients include one or more base oils and an assortment of additives (some are preblended, known as adpacs). The blending is done by either batch or inline. For a variety of reasons, the concentration of these ingredients can be off-formulation and alter performance. So too, a particular ingredient might be left out entirely or added by mistake.
Cross-Contamination
Cross-contamination relates to the accidental mixing of different and incompatible lubricant formulations. At times the effects can be negligible, but in other cases, lubricant performance can be impaired. Cross-contamination can occur many different ways. Because many blend plants don’t used dedicated tanks, hoses, lines, pumps or filters, there is always risk of product carry-over from an earlier batch.
Holding tanks are often only gravity drained between batches (no flushing). For many plants, there is generally an attempt to pig-out lines of residual oil and/or flush them with base oil. Still, even the best efforts might still leave trace concentrations of nonconforming additives. For lubricants shipped in bulk transports, uncleaned tanks and tank compartments (or leaky compartments) can result in cross-contamination.
Contaminated or Off-quality Feedstocks
Many blend plants check the quality of their feedstocks (raw materials such as additives and base oils) regularly. However, not all plants have the analytical ability to cover the range of potential nonconforming properties and contaminants that can occur.
For instance, it is rather uncommon to find a particle counter at a blend plant laboratory. Even elemental emission spectrometers may not be available onsite. Some blend plants perform only physical properties testing on each batch (viscosity, flash point, etc.).
Contaminated Packages or Transports
The cleanliness of new lubricants varies considerably. New lubricants often exceed recommended cleanliness levels for in-service lubricants. I’ve seen high-performance filters used by some blend plants to clean new lubricants. I’ve also seen no (or coarse) filters used.
It is also common to find containers (drums, pails, bottles) on packaging lines and conveyors left open (exposed to atmospheric dust) for extended periods of time before they are filled and sealed. Bulk transport trucks may sit with their top bungs open before, during and after loading. All of these conditions can lead to both particle and moisture contamination.
Mislabeling
This can occur by human agency as well. Due to the many different lube products that are handled, dispensed and packaged by blend plants and distributors, a lubricant can accidentally be introduced into the wrong package or a package might be mislabeled.
It is good to ask your lubricant supplier to provide you with a certificate of analysis (COA) for lubricants that will be used in critical applications. The COA, depending on the application, would confirm the following:
- Quality of the base stock(s). These are generally physical properties tests, including viscosity and flash point.
- Additive quality and concentration (treat rate). Knowing that the right additives are in the blend at the correct concentration can be determined by specific tests.
- Lubricant performance. This relates to the collective influence of base oil(s), additives and contaminants and their physical and chemical interactions. For instance, the right additive can improve demulsibility while the wrong additive or contaminant can impair this important property.
- Thickener performance properties. For grease products there are specific properties and tests that relate to the thickener and its interaction with the base oil and additives.
- Presence of contaminants and foreign additives. It is just as important to test for what’s not supposed to be in a lubricant as it is to test for what you are expecting. Batch inspection tests by blend plants may test only for properties they expect - not those they don’t expect. For instance, if elemental analysis is not performed on new turbine oil (because no organo-metallic additives are used and therefore not expected), accidental cross-contamination by a motor oil may not be detected.
Table 1 lists specific lubricant tests that can be applied to assess these five quality characteristics of a newly formulated lubricant. The selection of these tests, either for inspection of incoming lubricant deliveries or as a part of the COA supplied by the blend plant/distributor or both, needs to be carefully and judiciously considered.
Not only must the tests be selected but also the condemning limits. Because testing is expensive, the scale of the testing of new lubricants needs to be “right sized” and factored into the cost of lubricant procurement.
Following are some suggestions and strategies for selecting new-lubricant inspection tests:
- Consider tests that can screen a variety of properties and performance characteristics all at once. Good examples are elemental analysis, demulsibility and FTIR.
- Prioritize those tests and properties that are essential to lubricant performance and machine reliability in the target application. Good examples include viscosity, viscosity index, oxidation stability, cleanliness and dryness.
- Consider tests that would quickly reveal a property relating to a specific quality concern, if any.
- Keep testing streamlined and efficient. Run expensive and/or time-consuming tests only on exception, triggered by a nonconforming result from a screening test.
- Develop a consensus with your lubricant supplier on which tests will be performed and what the condemning limits will be.
Another important benefit for testing new lubricants is to establish a baseline for routine used-lubricant analysis. Even when new lubricants are well within acceptable quality limits, there may be considerable variations in physical and chemical properties (batch to batch). For instance, viscosity can vary +/-10 percent from the ISO VG midpoint (46 or 68, for instance) and still be “in grade.” Cautionary limits are sometimes set at +/-5 percent from new lubricant viscosity. Hence, the specific new lubricant viscosity must be known.
By taking an active role in testing new lubricants and giving constructive feedback to your supplier, incremental improvements in lubricant quality are bound to result. Lubrication excellence is a collaborative process. Lubricant quality is a measurable property. If it’s important . . . measure it.
About the Author
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Jim Fitch, a founder and CEO of Noria Corporation, has a wealth of experience in lubrication, oil analysis, and machinery failure investigations. He has advise...
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