Every year, the Society of Tribologists and Lubrication Engineers holds its annual meeting. Before I go any further, I want to clarify the meaning of the word tribologist. My favorite definition came from a friend, Dr. Tayeb Benchaita. I worked with him at Pennzoil a number of years ago. Tayeb said that a tribologist is trained in the science of friction, wear and lubrication, three disciplines working together to improve the world. Ive always liked this definition because it addresses the cornerstones of our business.
At the last STLE meeting in Atlanta in late May, the Engine & Drivetrain Panel sponsored an open forum on engine testing that asked why we continue to use outdated tests for modern engine oils. For many of you, the tests used to evaluate engine oils and set category limits are simply a name, such as the Sequence V or Sequence VIII. Many of these test protocols are designed around older engines, which many feel cannot begin to predict the lubricant requirements of new generation engines.
I can assure you that developing a new oil specification or category is a complex, time-consuming process. Our intentions are always to do the right thing, but often we get blindsided by unforeseen issues. This process often puts us in the position of being less timely and innovative in meeting the needs of the market. One obvious case is the current slog towards ILSAC GF-6. It seemed so simple until we found out that we needed three new tests and four major revisions to existing tests.
Angela Willis from General Motors, newly named chairperson for ASTM Internationals Passenger Car Engine Oil Classification Panel, presented a call to action at the December meeting of the American Petroleum Institutes Auto Oil Advisory Panel, outlining a process to speed up the development and acceptance of GF-6, the next passenger car engine oil upgrade. In addition, she identified a long-term opportunity to help improve AOAPs development process. For starters, there is a need to clearly define roles and responsibilities of the various surveillance panels and task force teams. She also noted the need for clearly defined gates with established deliverables in the overall specification development process.
Willis went on to call for a clear delineation of when a test is in or out; that is, whether or not it will be a part of the new category. That decision, she believes, needs to be made much earlier than when it happens under the current process, which is after the test precision matrix has been run and the test results are blessed by AOAP. The delays due to precision matrix testing and subsequent statistical precision analysis result in continuous category delays. The hope is that this would help reduce the amount of investment in a problematic test.
One of the critical issues here is that engine technology is advancing rapidly and the oil development process is lagging far behind. You only have to look at the API SN Plus effort to see what I mean. To my way of thinking, API SN Plus and SN Plus-Resource Conserving are essentially ILSAC GF-6 already. The engine designs that the original equipment manufacturers knew would need an improved oil are in the marketplace now and have been for some time. The oil approval process leading to GF-6 is now not likely to be introduced until late 2019 at the earliest, or maybe 2020. The OEMs want to see market-general API categories move in concert with engine upgrades. They have a dilemma and are constantly trying to resolve it.
One solution that has become more likely is to go back to having each OEM specify its own engine oil. Thats where we were in the late 1960s and early 1970s, when API came up with the original service category system. If that were to happen, oil marketers would be faced with supplying multiple products and labels, which is a logistics nightmare. Its tough enough with the three common types of engine oil (conventional, semi-synthetic and full synthetic) in addition to multiple viscosity grades and specialized products such as high-mileage oils.
At the STLE open forum, concern was expressed that we are likely to be testing tomorrows oils in yesterdays engines. You might ask yourself what that means. I think that the whole concept of backwards compatibility may actually be dragging down the process. Our friends at APIs Lubricants Group might be very upset with my thoughts here, but one of the reasons we stay with old engines is to tie current oils back to earlier categories so the existing fleet can still get the oils it needs. Sure, there is a lot of history with the sequence tests, but I can tell you for a fact that, for example, todays Sequence IIIG test for oxidation and deposits is a far cry from the early Sequence IIIA. The table below highlights the differences.
As you can see, these two versions of the Sequence III have very little in common. The IIIG is run in a smaller engine at higher loads and speeds. The oil temperature is higher and the test is longer. Seems like that should cover anything from the IIIA. However, the IIIA engine is a flat tappet engine, while the new GM engine has roller followers. That means differences in antiwear performance.
The other sequence tests, particularly the Sequence IV and Sequence V, are also quite different in their current form versus their original engine designs. The only engine that has remained relatively constant is the Sequence VIII, which used to be called the CLR L-38. The only change to it was replacing leaded with unleaded gasoline.
Oil chemistry has changed as the needs of newer engines have changed. Theres more antioxidancy and friction reduction, while dispersancy and detergency have remained relatively the same. Thats especially true since the general introduction of unleaded fuel.
Reference oils are another issue. Whats a reference oil, you ask? It is an oil that has a history of performing in a certain manner in a particular engine test. Running reference oils (usually a failing and a bare passing oil for each sequence test) takes up a fairly large portion of an engine test labs test stand time. They are run on a regular basis in order to make sure an engine is within operational parameters. If there is a change detected, adjustments are made to the test stand to bring the test back into compliance.
The reference test results for each engine running a particular sequence test are reported to ASTMs Test Monitoring Center, and the results are compared to all the other stands. If a clear tendency shows up, it may be cause to make adjustments to operating conditions or declare a test method to be out of compliance. Often thats the result of a change in the fuel or a new set of parts being tested. At any rate, its more drag on the system.
The issue for the OEMs, and for oil marketers to a degree, is how to streamline the system to make sure the OEMs get the oils they need in a timely fashion. Lets face it, the quest for ILSAC GF-6 is now going into its seventh year, with at least 18 months to two more years to go. API SN Plus has taken some of the pressure off, but it is a patch and not a true advancement-or maybe it is the wave of the future.
I, for one, would like to see some demarcation of the backwards compatibility issue. We could have an oil that covers the pre-1990s flat tappet era and a new oil that might make it easier for oil marketers. We have been marketing a high-mileage oil for some time now. What would be the problem with marketing an old API category for this, such as SG? Maybe we need a single engine test to verify the old oils. Theres bound to be an engine that could be used for this purpose.
Next, how about we combine some of the veteran tests to reduce the number required? It might be possible to develop an engine test that combines the Sequence III, Sequence V and Sequence VIII requirements. Quite frankly, I dont think that there has been much movement in the performance requirements for these three tests for some time now, except for the introduction of newer hardware to run the tests. I admit that it would be a real challenge to do it, but once done it would be less to drag along.
Is it also possible to include the Sequence IV in a combined test? The Sequence IV will be run in a Toyota engine and is the only sequence test engine not built by a North American OEM. Perhaps the Japanese Automobile Manufacturers Association would be willing to take on the task of developing the mixed sequence test engine and procedure.
That leaves the Sequence VI, IX and X. These tests are much more specific to needs that are perhaps not universally required. Fuel economy (Sequence VI) is a need for OEMs because of government regulations, while low-speed pre-ignition (Sequence IX) and chain wear (Sequence X) are needed for specific engine designs that are currently in vogue, not older vehicles. These three, plus the combined procedure, would define ILSAC GF-6. In the future, the combined test could be a baseline and specialized tests would be added or subtracted as required.
Theres no question that the process to develop a new category is difficult. New requirements mean new tests may be needed. However, if some of the work can be reduced or even eliminated, it would make for a quicker turnaround and more efficient use of our resources as an industry.
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 and SAE International, where he was chairman of Technical Committee 1 on automotive engine oils. He can be reached at email@example.com.