If there is one word I hear every day as it relates to automotive lubricants, it’s “synthetic.” Twenty-five years ago, the same word elicited a totally different response than it does today. We were just starting to enjoy the technological advances the oil refining industry was achieving. The world of new and improved base oils for automotive lubricants was gaining momentum. We no longer had to depend on solvent-extracted base oils (Group I), and the new hydroisomerized base oils (Group II and III) were becoming a cost-effective, higher-performance alternative to the higher-priced polyalphaolefins (PAO, Group IV) and ester-based oils (Group V). What to call these new base oils became one of the most contentious debates over the origins and terminology of what qualifies as “synthetic” base oil, with a definition proving to be so difficult the “absolute” definition has remained in limbo to this day with no end to the confusion in sight. Much of the responsibility for this confusion can be placed on base oil manufacturers, oil companies, and lubricant marketers looking to upsell their competing products.
This whole thing got started in the 1990s when the lubricants industry wanted to persuade the API (American Petroleum Institute) and SAE (Society of Automotive Engineers) to set a standard or official designation for the newly available mineral oil-derived hydroisomerized base oils. The argument was based on the development of very high viscosity index (VHVI) base oils that provided properties “similar” to the PAOs and ester base oils but cost much less to produce. Hydroisomerized base oils (Group II, III, III+) are created by chemically converting the molecules of the selected mineral oil feedstock to a different set of molecules, mainly by chemical rearrangement or decomposition of the structure of the feed molecules. PAOs (Group IV) are derived from a chemical process that combines small molecules to make larger, more complex molecules of a desired type and length. Esters are the most common synthetics in Group V. Group V base oils are defined by API as any type of oil other than mineral oils or PAO lubricants. Esters are formed by combining an acid with an alcohol by the process of esterification into long-chain lubrication molecules valued for their polarity and excellent lubricity. At that time, it was all too much for the API and SAE to determine a winner. Ask a blender of oil products formulated with hydroisomerized mineral oils, and you get a definition of “synthetic” base oil that involves equivalent performance, cost-effectiveness, and consumer choices. Ask the same question to a blender involved in the production of PAO or esters, and how the product is “constructed” will be the determining factor when calling a base oil “synthetic”. In 1995 and 1996 respectively the API and SAE removed references to the word “synthetic” from its terminology books and guides with API removing references to “synthetic” from its Engine Oil Licensing and Certification System.
In a ruling released in April of 1999 the National Advertising Division (NAD) of the Better Business Bureaus issued the first basic ruling concerning using the marketing term “synthetic” (allowing PAO or hydroisomerized base oil products used in automotive lubricants to be called synthetic) was now setting the stage for a much broader description to be used in the future for the marketing of automotive lubricants.
When these proceedings occurred, understanding the scope of these “new” improved base oils and their availability was important when trying to understand the market-driven reasoning behind the definition of “synthetic base oils” that became so difficult. The PAO commercial market was an offshoot of government programs in the 1950s to create superior base oils for demanding military contracts. Operational requirements for extreme climates and severe duty made the PAOs perfect for the military and drove manufacturing and development to the point that commercialization was possible even though the PAO base oils were much more expensive than conventional ones. By the early 1970s, specialized PAO products began to appear, with Mobil 1 products becoming a major consumer-purchased product. The invention of the hydrocracking process in the 1950s, followed by the development of hydroisomerizing in the late 1980s by Chevron, set the stage for the development of the Group II, III, III+, and GTL (gas to liquid) base oils that now dominate the base oil marketplace.
When the BBB/NAD (National Advertising Division) ruling was made in 1999, only a handful of refineries actually produced PAO or hydroisomerized base oils. The majority of engine oils and transmission fluids of that era used solvent-extracted Group I base oils with their own proprietary additive packages to blend their automotive products. The new Group II and III base oils were more costly than the solvent-extracted Group I base oils, with the PAO base oils costing twice what the hydroisomerized base oils were. Dealing with high-performance products that cost significantly more than the lesser-performing but currently available oil products, the aftermarket service industry was faced with a marketing dilemma: How to differentiate the new products with an unmistakable designation that immediately implied “high performance.” Calling the new base oil options “synthetic” was the answer.
Technology-driven engineering to improve efficiency for improved fuel mileage in the early 2000s also drove the use of hydroisomerized and PAO base oils for the formulation of fuel-efficient reduced viscosity engine oils and transmission fluids. For these applications, both types of “synthetic” base oil are assembled to a desired weight, molecular length, and performance level appropriate for the desired application and service. Most importantly, they could be used to make low-viscosity 0W and 5W grade engine oils and the new ULV automatic transmission fluids, which have now become the new standard.
This transition from Group I to Group II, III, III+ and Group IV and V base oils has changed the worldwide refining capacity dramatically since 1999. Group I base oils production has declined, and PAO and hydrotreating refineries have sprung up all over the planet, with the availability of hydroisomerized Group II, III, III+, IV, and V base oils increasing every year. There are some who argue (mainly producers of Group IV and V base oils) that the quality of hydroisomerized Group II, III, and III+ base oils is inconsistent, and their physical properties are different from one manufacturer to the next. Blenders that use the lesser quality Group II, III, and III+ oils for the “synthetic” markets will mislead consumers, and the higher niche market for high-performance products that have evolved will erode and eventually disappear.
From what I see and hear, this is not the case. The market competition that has occurred has created a marketplace full of products, all claiming to be synthetic. Most consumers see little to no difference in their opinion, other than some synthetic brands cost less than others. With little understanding or concern, there may actually be a difference in outcomes if you choose to go with the less costly products.
This failure to differentiate products has resulted in the confusion we see and hear every day about whether you manufacture, sell, or use engine oils or transmission fluids. I have never hesitated to explain the complexity of the situation to those interested enough to listen to the technically confusing answer. No matter how you feel about it, there is merit to each party’s argument when trying to define what a synthetic base oil is and why one would be more desirable than the other. Both options offer improved levels of performance over solvent-extracted Group I base oil, but there will always be a certain amount of Group I used in any formulation because Group I base oil is used as a diluent for dissolving and incorporating additives used in the additive package all automotive engine and transmission fluids contain.
Both synthetic base oil options often mix different viscosity base oils (PAO or hydrotreated base oils) to target the desired viscosity for the desired fluid type. In the end, there is still considerable concern about the message consumers are getting. As you have probably concluded by now, even the experts can’t agree on a definition of what synthetic on the label of a bottle of engine oil or transmission fluid truly means.
The best guideline I can give is to read the technical data sheets provided by the manufacturer of any engine oil or transmission fluid you are considering purchasing. Understand the performance properties you are looking for and make sure the product meets your expectations. Group II and III base oil products are generally less costly than the PAO or Ester-based base oil fluids and can offer great value. True synthetics like PAO and Ester-based fluids will continue to offer significant performance advantages, including high and low-temperature performance under extreme conditions with better oxidative stability and lower viscosity for the newest technology, but expect to pay a premium.
What is certain is that “synthetic” as an indicator of higher performance will remain on labels and specification sheets from now on. It’s up to the end user to decide which type of “synthetic” best meets their performance or economic preference.
