Oil is oil one commonly hears, but most of us in the lubricants industry know such statements are just wrong. They do a disservice to base oil and additive manufacturers, formulators and the many blenders who work hard to make and deliver quality products with superior performance. You bet there are differences in motor oils, and some are significant and meaningful to consumers. One of the clearest examples is seen when comparing conventional motor oils to synthetics.
Synthetic motor oils are made with more pure, more stable base oils that typically outperform conventionally refined products in the areas of low- and high-temperature endurance, fuel economy, shear stability, and the opportunity to extend drain intervals. These benefits can well justify the premium paid for synthetics, especially for consumers with high performance engines or those driving under adverse conditions. But aside from reading and trusting the label on the container, how can one ever be sure a synthetic motor oil is in fact a synthetic?
The first and most common answer is to send it to a lab; they can test the product to see if its synthetic. But can they?
Commercial laboratories with experience in petroleum product testing may suggest tests to characterize the composition of the oil, including gas or liquid chromatography, nuclear magnetic resonance, GC mass spectroscopy, infrared spectroscopy, thin-layer chromatography, and other sophisticated and expensive tests that tease apart and quantify molecules by hydrocarbon numbers and structures. In addition, they can test for sulfur, phosphorus, oxidative stability, viscosity index, Noack volatility, pour point, foaming and other physical and chemical properties. If one has the bucks, the labs even will run full engine tests such as the ASTM Sequence IIIG, VID, VG, VIII and more.
But the fact is, even if one were willing to part with a half-million dollars or so for tests to assure a product is synthetic, the answer would come up short. Because although test data can be very helpful in characterizing the molecules in the motor oil and may support a belief that synthetic base oils are present, and although engine test can reveal meaningful differences in performance, tests cannot unequivocally prove that a motor oil is synthetic.
And there are several reasons why.
First, there are no industry standards or specifications that define synthetic motor oil. And maybe for good reason. Motor oils are a complex and delicately balanced mixture of base oils and chemical additives formulated to meet API, ILSAC, ACEA, OEM and other specifications. These specifications are clear and measurable. They are also blind to the word synthetic. This is because they are performance-based specifications, not directly tied to the oils composition. In the absence of official definitions or discriminating specifications, the word synthetic has evolved to be more of a marketing term than a technical term in the world of automotive lubricants. (One exception is Germany, which still reserves it for products made with non-mineral-oil bases such as polyalphaolefins.)
Second, even if one draws a line arbitrarily in the sand that says synthetic motor oils must contain X percent API Group III, IV or V base stock, that line would be muddied and very difficult to confirm by testing. In fully formulated motor oils, the differences between a high-quality Group II base oil (deemed conventional) and a low-end Group III (synthetic) are so small as to elude even sophisticated testing protocols. The same applies to viscosity index, saturates content, Noack volatility and other physical properties, which can be altered through additives or base stock blends. For example, while a Group II base oils viscosity index falls short of a Group IIIs, V.I. can be adjusted with the use of additives and/or base stock correction fluid to reach the level of a Group III.
Its also important to understand that engine oil additive packages typically contain about 40 percent to 50 percent base oil, as a diluent or carrier fluid. This component can change the hydrocarbon profile of the final lubricant, further complicating the ability of laboratory testing to distinguish between conventional and synthetic.
This is not to say its impossible to come up with a working definition of synthetic base stocks or motor oils. Indeed the industry already draws a line between the use of Group II and Group III base oils. But the line functions under an honor system, with no way to monitor or verify the actual base oils used in finished motor oil that claims to be synthetic. Perhaps if the industry developed a written, officially endorsed and more technically meaningful definition for synthetics, blenders and consumers would enjoy even greater benefits.
But if or when a definition for synthetic motor oils is written, it is important to consider that the market continues to move forward. Synthetics are slowly becoming the norm, as specifications ratchet up and Group III supply grows. With that, the cachet of being synthetic will likely dissolve into yesterdays news. What then?
Now is time to start thinking about the next tier in motor oils. A tier that rises above synthetics. A tier that offers a step-change in performance, much as synthetics did when they entered the market. And this time around, we might consider laying a better foundation for the tier to grow. It should offer meaningful and measurable performance advantages that clearly separate good, better and best, through defined and supported performance specifications.
Tom Glenn is president of the consulting firm Petroleum Trends International, the Petroleum Quality Institute of America, and Jobbers World newsletter. Phone: (732) 494-0405. E-mail: tom_glenn@petroleumtrends.com