The purpose of older engine tests is to ensure the quality of oils licensed to earlier categories rather than protecting specific engine technologies, points out a member of the Engine Manufacturers Association.

Although products licensed to the American Petroleum Institutes one-year-old CK-4 and FA-4 HDEO categories are rapidly being accepted in this market, earlier categories, including API CH-4, CI-4 and CJ-4, still predominate. At the end of 2016, CJ-4 held 75 percent of the global HDEO market, followed by CI-4 at 15 percent, CH-4 at 5 percent and CG-4 at about 4 percent, found Parsippany, New Jersey-based consultancy Kline & Co.

Older HDEO categories are still needed to service machines around the world because of heavy-duty engines lengthy service life and equipment operators cost sensitivities, which are well served by older categories, the EMA member stated. This is particularly true in developing countries, where it is typical to see 30- or 40-year-old machines in service and HDEOs considered obsolete by API, such as CF-4 and CG-4, still sold. Without older tests or some way to bridge to newer tests, there is concern for OEMs that still service these machines with parts and technical support, the source added.

Checking the Pulse

The fate of HDEO tests, such as Caterpillars single-cylinder engine tests and a couple of Cummins wear tests, appears to be the next issue facing the heavy-duty engine oil industry.

The reality is that tests like the Cat 1N, Cummins ISM, Cummins ISB, and even the Mack T12 support not only those older categories, but also the most recent ones, including API CK-4 and FA-4, said Shawn Whitacre, chairman of ASTM Internationals Heavy Duty Engine Oil Classification Panel. The Mack T12 test measures wear performance of oils in turbocharged intercooled diesel engines equipped with exhaust gas recirculation and using ultra-low-sulfur diesel fuel.

Engine test availability has been the subject of an ongoing discussion between Whitacres group and APIs Diesel Engine Oil Advisory Panel, with the consensus being that at least three or four years of test availability remains for all currently required engine tests. However, two tests are in question: Navistars Engine Oil Aeration Test and the Sequence IIIF, which measures an oils resistance to thickening, varnish formation and wear. Both relate to earlier categories and are necessary to meet active category requirements.

Both tests are currently under review by the Category Life Optimization Group at API. The Sequence IIIF is in the process of being read into the new Sequence IIIH with limits and final balloting to be rolled out early this year, while the new Caterpillar Oil Aeration Test is being evaluated against the legacy test and expected to be successfully introduced later this year.

Another question is whether existing tests can be supported, especially those using older hardware such as the Cat 1N, the Roller Follower Wear Test and even the Cummins ISM. As engines and replacement parts to support these tests become more difficult to acquire, OEMs have greater incentive to reconcile their relevance-especially when new tests enter the scene.

CLOG has been tasked with finding ways to read from newer tests back to older tests in order to maintain category viability, as maintaining backwards compatibility and securing funding for tests to demonstrate equivalence is always challenging.

Some of the legacy tests may not fully represent modern engines. For example, newer engines equipped with soot control devices dont generate as much soot, which means the older, high-soot wear tests may not correlate to current field conditions, commented Greg Braziunas, performance engineer at Daimler Trucks North America. That may signal a loss of interest in maintaining tests such as the Cummins ISB and ISM.

The Prognosis

Ryan Denton, lubricant technical specialist at Cummins Inc., told LubesnGreases that his company does not have an urgent need to replace the ISB and ISM tests, since its parts supply for both seems to be secure for at least three years. He added that Cummins has reviewed both tests internally and performed some preliminary testing on newer engine platforms to assure it is prepared to act quickly on new test development if and when a parts shortage or other issue spurs the need for a replacement test.

In addition, we know that these tests, along with Mack tests, push forward a high-soot dispersant requirement on diesel oil, which is a major question in backwards compatibility, Denton stated. Cummins would consider introducing a lower-soot version of one or both tests in conjunction with the latest versions of its 4- to 7-liter B series engines and 11- to 15-liter X series engines. How that would interact with future categories is difficult to predict.

Cummins does see a need for tests that address rolling and sliding overhead engine designs in future API categories, Denton noted. In sliding designs, valve followers slide over the cam lobes, setting the timing for each valves opening and closing.Roller followers have a rolling bushing that follows the cam lobe, which is more resistant to wear than the sliding follower.

Soot limits could change, and engine hardware could modernize. However, Denton stated, the need for wear protection in the important boundary and mixed lubrication regimes will continue well into the future.

What impact would there be if these older engine tests are retired? API rules state that if a test is no longer available, the categories it serves become obsolete.

Bob Salgueiro, industry liaison for Infineum, said that if OEMs feel there is still a need for older API commercial categories-due, for example, to regional differences in fuel sulfur levels and emissions equipment-the lube industry needs to develop a way to maintain these specifications by supporting the development of new tests that are backwards compatible with older categories.

Salgueiro noted that there are a number of protections in the heavy-duty diesel side of the industry to prevent the sudden obsolescence of an engine test. ASTMs Test Monitoring Center provides an update on critical engine test parts biannually, and ASTM test surveillance panels work with OEM test sponsors and critical parts distributors to ensure a continuing supply of parts for the engine test.

OEMs that have key engine tests in API categories note that they all are aware of the challenges in developing a new test, Salgueiro continued. It could take years to develop a replacement test or months to identify suitable limits in a newer test.They know the hurdles and know to communicate early if obsolescence is on the horizon.

Preventive Care

The issue of adding new HDEO tests was discussed last March at a meeting of APIs Diesel Engine Oil Advisory Panel and ASTMs Heavy Duty Engine Oil Classification Panel, which focused on reviewing the results of the then-recently introduced API CK-4/FA-4 categories.

The meeting was prompted by the emergence of the Ford 6.7L diesel engine wear test and the standardization of Daimlers DD13 scuffing test. Neither of those tests were ready in time to be included in API CK-4/FA-4 but are viewed, at least by the test sponsor in each case, as critical to defining the performance of oils used in their engines.

The Ford test is particularly relevant. Ron Romano, service lubricants technical expert at Ford, said that the OEM has been very concerned about the wear problems the 6.7L test identifies with low phosphorus oils (less than 1,000 parts per million), including the new CK-4/FA-4 products.

Romano said that some CK-4 and FA-4 formulations may not be as robust on wear protection as existing API CJ-4 formulations containing more than 1,000 ppm phosphorus, and noted that Ford has seen accelerated 6.7L valve train wear with the new oils that it hadnt encountered with CJ-4 formulations. Ford warned customers against using CK-4/FA-4 oils and issued a new specification, WSS-M2C171-F1, to deal with these concerns.

One meeting participant suggested that the industry come up with a CK-4 Plus category to include the Ford 6.7L wear test and possibly the DD13 scuffing test. The category would be similar to API CI-4 Plus, though field failure would not be the impetus for its creation, as was the case for past category additions.

Participants also cautioned that a potential enhancement to API CK-4 using the Ford 6.7L test might cause a regression to CJ-4 phosphorus levels, which were lowered to address emissions targets. Dan Arcy, co-chairman of DEOAP, said that, to date, no one has formally proposed a CK-4 Plus category to support Fords needs.

There is ongoing discussion among OEMs, oil marketers and additive manufacturers about keeping HDEO tests that use older engines. On the one hand, OEMs are concerned with the ability to maintain the hardware for the existing tests, as they are responsible to the end user for satisfactory hardware performance. The EMA is working with other industry stakeholders in the Lubricants Standards Development Review Group to determine how best to tackle these issues.

Oil marketers are concerned with the performance and cost of their products and bear the responsibility for the quality of oils produced and delivered to trucking fleets and owner-operators.

Additives suppliers serve the role of making the upfront investment to develop products. And the independent engine test laboratories, like Intertek and Southwest Research Institute, have the responsibility of creating sufficient test capabilities to meet the needs of the additive suppliers and other customers.

Engine oil formulators view base oil interchange as an important part of engine oil development programs. Defined in Annex E of API document 1509, base oil interchange allows finished lubricant producers to substitute an equivalent base oil in their formulations, without repeating costly engine tests, and while still maintaining a products API license. While BOI is well established for API Group I and Group II base oils, very limited interchange is allowed for Group III. Given the rising use of Group III base oils, this issue must be resolved in order for satisfactory BOI to occur at reasonable cost.

Which tests are covered under the interchange rules is another vital concern. For examples, if the Volvo T-13 engine oil oxidation test is required for interchange, it adds a great deal of time and cost to any interchange program, as it takes about twice as long to run as the Sequence IIIH and costs about twice as much. Incorporating the Sequence IIIH into API CK-4 and API FA-4 for base oil interchange purposes could be a better option instead of running the Volvo T-13 test for each base oil. The Sequence IIIG was used for this purpose in API CJ-4.

It is certain that new heavy-duty engine oil categories will demand new test hardware and protocols. How will the industry tackle these needs while maintaining the vitality of older categories?