It must seem like youve heard this same theme over and over. I know that it gets old, but the whole story of emissions and fuel economy is the main driving force behind engine hardware and engine oil developments for the last half century. I know this because I was already working in the oil industry when it all started.
Emissions came first. Arie Jan Haagen-Smit from the California Institute of Technology first identified smog when he collected some air in Pasadena, California, in a vacuum trap back in the early 1950s. He discovered some ugly stuff, which he analyzed and found to be a mix of things that come out of the exhaust pipes and road draft tubes of cars and trucks. The compounds were toxic, carcinogenic and generally unhealthy to breathe. It was easy to catch these nasties, since Pasadena had some pretty foul air at the time.
Why do I mention this? Because the past 50 years have seen an absolute explosion in engine design and engine lubricant improvements to reduce pollutants and greenhouse gas emissions. I wish I could say that engine oil improvements caused engine design changes, but the truth is the engines have led the lubricants. Its not that lubrication research doesnt exist, but rather that lubricants are developed as a result of hardware changes.
If you are having trouble sleeping some night, try reading the American Petroleum Institutes 1509 Engine Oil Licensing and Certification System document. It is the bible of engine oil category development. Annex A describes the history of engine oil specifications. The opening paragraphs explain how we got to the S (gasoline) and C (diesel) category designations, a major descriptor of engine oil quality. Heres a bit of the history detailed in Annex A that relates, in my mind, to the massive changes that have occurred in the years since 1970:
In 1969 and 1970, API, ASTM and SAE established an entirely new classification system that would satisfy the changing warranty, maintenance and lubrication requirements of the automotive industry. SAE initially determined that there were eight separate Service Categories of passenger car engine oils of current substantial commercial interest to be considered. ASTM established the test methods and performance characteristics and technically described each of the Service Categories. API prepared a user language, including new letter designations for each of the eight Service Categories. These eight engine Service Categories were tied to the ASTM technical description and primary performance criteria. SAE then published results of the entire project and the methodology as SAE J183.
Youll notice that this was a joint effort by oil marketers and engine manufacturers to get a logical system of oil performance in place without completely killing brand identity. Even then, there were some oil marketers that felt this system would turn engine oil into a commodity. Surprisingly, it didnt.
About the time that this system was put in place, Haagen-Smits discovery and identification of certain air pollutants led to the start of emissions controls on automobiles. The Clean Air Act, passed in 1970, required such measures as positive crankcase ventilation, which meant that blow-by gases trapped in the crankcase could no longer be allowed to vent to the atmosphere. Some estimates said these gases were the source of 50 percent of all auto-related emissions. Instead, they were recirculated back through the intake manifold. The impact on engine oil formulations was essentially nil.
1973 brought us the first Arab Oil Embargo. I dont know if you were a victim of that ordeal but I can tell you it was no fun. (See my April 2018 column.) Congress reacted swiftly by passing the Energy Conservation Act of 1975. That legislation established fuel economy mandates, which led up to the 27.5 miles per gallon corporate average fuel economy (CAFE) standard. In 1977, the Clean Air Act was amended to include a schedule of emissions reductions and leaded gasoline was feeling the first threats to its existence.
By 1980, most passenger car engine oils included the above-mentioned additives along with friction modifiers. Preferred viscosity was SAE 10W-30, although demand for SAE 5W-30 was growing rapidly. In addition, a new category, API SF, was introduced to provide better wear protection. Fuel economy was being measured against an SAE 25W-30 reference oil using a five-car chassis dynamometer procedure to determine what percentage of fuel consumption could be saved.
Leaded gasoline reduction regulation was introduced in 1985, which restricted lead to 0.10 grams per pound. It would be 1996 before all lead was removed from fuel. The three-way catalyst was introduced in the same timeframe and became the next influence on engine oil when it was discovered that zinc dialkyldithiophosphate could poison the catalyst and actually form zinc pyrophosphate, which physically blocked the catalyst bed. Over the next several years, ZDDP levels in engine oils were reduced.
In 1989, API SG was introduced to the industry. Although it didnt raise the performance level of engine oils significantly, it did represent a change in engine tests and hardware. It was at this time that API and the Alliance of Automobile Manufacturers, a predecessor to the International Lubricant Standardization and Advisory Committee, began working together to improve the system. In its historical discussion of oil categories in API 1509 Annex A, API notes that, In 1992 and 1993, API, ASTM and U.S. and Japanese automotive manufacturers introduced improvements in the licensing process for engine oils to ensure the quality of products being marketed and to enhance consumer awareness of the recommended lubricants for new vehicles. This improved process is known today as the API Engine Oil Licensing and Certification System (EOLCS).
With the general availability of non-leaded gasoline, most of the existing engine tests were re-configured for unleaded gasoline; test procedures were either redesigned or new ones were introduced. The new engine oil service category was API SH, which contained less ZDDP, more antioxidants and other additives mentioned earlier. There was also an apparent push for better deposit control. It was the first oil category to carry the dual designation of API SH/ILSAC GF-1. The GF standard represented only the following viscosity grades: SAE 0W-XX, SAE 5W-XX and SAE 10W-30.
Why call it GF? Because original equipment manufacturers wanted an oil designation that was evergreen, that wouldnt change even if the performance level of the oil did. They felt that an owner would be less likely to use an oil that didnt meet their required vehicle needs. The methodology was to use a symbol (the starburst) that was easy to see and meant the oil was okay for the latest car and light truck needs. The GF standard mirrors the API categories, plus it includes fuel economy tests such as the ASTM Sequence VID.
By 1996, the next category, API SJ, was introduced and ILSAC GF-2 was incorporated. The restriction in ZDDP was at 0.1 percent weight of phosphorus. In addition, restrictions were placed on volatility. There was concern that excessive volatility would result in oil consumption issues. Five years later, API SL/ILSAC GF-3 was approved. This marked the first category to be approved only on unleaded fuel test engine procedures. Phosphorus levels were restricted, especially in the viscosity grades that were part of the GF standard.
API SM/ILSAC GF-4 was introduced in 2004 and further tightened both phosphorus and volatility limits and added higher fuel economy requirements. SAE 0W-XX became more favored because it brought better fuel economy results to the ILSAC GF-4 grades. In addition, there were incremental improvements in deposit and wear control.
The current engine oil standard, API SN/ILSAC GF-5, made its debut in 2009 and represents the latest limits in phosphorus, volatility and fuel economy. It is also the first category to require meeting the Sequence IVA cam lobe wear test. This test is the first international test (using an engine from a Japanese OEM) to be included in the required test procedures.
It was at about this time that legislation was introduced to further improve CAFE. In addition, emissions reductions were tied in to achieve better mileage and generate less exhaust from the tailpipe. New engines were designed to be more efficient. Several techniques were in the pipeline such as the gasoline-fueled, turbocharged direct injection engines. These engines can now achieve 140 horsepower in about 92 cubic inches, or 1.5 horsepower per cubic inch. My 283-cubic-inch V-8 Chevy from 1957 could get the same power, only it was 0.5 horsepower per cubic inch. Thats three times more efficient!
Throughout this long progression to the current API SN/ILSAC GF-5 there have been increased needs for engine performance and longevity, fuel economy and volatility improvements, as well as reduction in viscosity grades. Some of the changes have necessitated new base stocks, which has resulted in API Group II supplanting Group I as the core base stock. Group III and Group IV are being used to achieve lower viscosity and lower volatility in the most recent categories, especially for SAE 0W-XX grades.
The long-awaited API SP/GF-6 will be available sometime in 2020 with two completely new tests, the Sequence IX (to measure the potential for low-speed pre-ignition) and the Sequence X (timing chain stretch/wear). Because of the delays in getting ILSAC GF-6 in place (it is currently three years behind schedule), the Sequence IX has been incorporated into a new API SN Plus supplemental passenger car engine oil category.
The auto industry needed every one of these changes, and the oil industry responded. The task would have been impossible without the development work carried out by the additive industry and the diligence of ASTM. All of these folks deserve a big hats off from everyone.
Industry consultant Steve Swedberg has over 40 years experience in lubricants, most notably with Pennzoil and Chevron Oronite. He is a longtime member of the American Chemical Society, ASTM International and SAE International, where he was chairman of Technical Committee 1 on automotive engine oils. He can be reached at firstname.lastname@example.org.