What is in these oils, and which one is better?
A relatively common request to an oil analysis lab is to identify the ingredients in samples of new lubricants and/or determine which lubricant will perform better. While this is possible with laboratory testing, it requires vastly different testing than is routinely performed.
The predominant analysis on a report is elemental spectroscopy, and the keyword with its results is elemental. This test quantifies the elements in the various chemicals and compounds of the oil, it does not determine the levels of additives. Some additives may employ the same elements, but in different ratios to different effects, therefore higher levels cannot be assumed to necessarily be better.
Also, the test does not measure every possible element, only those commonly found, which means certain additives might not be detected at all. The following additives are essentially invisible to elemental spectroscopy: dispersants, rust/corrosion inhibitors, Viscosity Index improvers, anti-foam agents, emulsifiers, demulsifiers, and some forms of AW, EP or friction modifier additives.
A reasonable analogy would be using elemental spectroscopy on samples of sweetened coffee. Table sugar (sucrose) has a chemical formula of C12-H22-O11, and honey contains both glucose and fructose which have the chemical formula of C6-H12-O6. The results from the test would not identify the levels of each sugar, but rather the levels of carbon, hydrogen and oxygen. Since sucrose has a slightly higher ratio of carbon to hydrogen, it may possible to distinguish sugar-sweetened coffee from honey-sweetened coffee, but impossible to tell how much of each in coffee sweetened with both.
Now imagine coffee sweetened instead with Aspartame/NutraSweet, which has a chemical formula of C14-H18-N2-O5. Without measuring the nitrogen content, it can only be assumed a coffee has been sweetened with an artificial sweetener, given the vastly different ratio of carbon to hydrogen compared to natural sweeteners.
Returning to oil, the second part of the initial inquiry is to determine which product will perform better, which is akin to asking which coffee would taste sweeter. Sweetness can only be determined by trying (tasting) each sample, just as the performance of a lubricant can only be measured by trying it in an application. To that end, there are several laboratory tests aimed at simulating an actual trial, and some are modeled after realistic conditions, while others are purposefully accelerated with their results extrapolated.
Such simulation, or performance, tests run from hundreds to thousands to even hundreds of thousands of dollars per test, and take anywhere from a day to over a year to run. This kind of testing is not usually undertaken by end users, but rather by lubricant manufacturers and formulators, therefore it is generally recommended to inquire if results from this type of testing can be provided. Caution should be exercised though, since some of these tests have been acknowledged as not being a future indicator of performance, but simply a form of standardized benchmarking.
In summary, a commercial oil analysis lab cannot easily determine all the ingredients within a lubricant from routine testing, nor provide any reasonable insight over future performance. This type of information is only obtained directly from the supplier (if available) or at great cost (both time and money).
