Heavy Going for HD Oils

By Steve Swedberg

For those eager to see the market debut of the next heavy-duty diesel oil upgrade, known as PC-11, theres good news and bad news.

The good news is that all the engine sequence tests are in place for the proposed category, including two new ones that have moved along to matrix testing. These are the Mack T-13 test for bearing corrosion, oil oxidation and nitration, and the Caterpillar Oil Aeration Test. As this issue goes to press, various laboratories have installed the test stands and are preparing to put them through a structured matrix, running tests dozens of times with a hand-picked slate of engine oils to prove they can be counted on to discern between good oils and bad ones.

The bad news: The date when the American Petroleum Institute expects to begin licensing the oils now looks to be March 1, 2017. While individual products claiming to meet the new specification could be available earlier, no one may update the trademarked API Donut symbol on their products until that date.

Marketers will also need a way to alert buyers to the new oils high-temperature/high-shear properties, said Kevin Ferrick, engine oil licensing manager at API. PC-11 oils meeting current HTHS limits will be fully backwards compatible with todays API CJ-4 oils. Its been proposed that these could be labeled as API CK-4, although the final decision hasnt been made yet, he told LubesnGreases last month. That would be the next obvious progression after todays CJ-4 oils.

However, some PC-11 oils will have even lower HTHS viscosity, to deliver some fuel economy benefits, and these oils may not be suitable for use in older engines. So there is a strong desire to indicate the distinct differences between these two, probably by using the Donut, Ferrick went on. To avoid misapplication, the low-HTHS oils might get their own designation in the Donut, possibly API FA-1. Those decisions will come later from APIs Lubricants Group.

Matrix Cost: $5M

The other piece of the PC-11 puzzle that is finally falling into place is funding for the matrix tests. Ferrick confirmed that in mid-September a formal memorandum of agreement was signed by the key stakeholder groups: API, representing the oil industry; the American Chemistry Council, which speaks for the additive manufacturers; and EMA, the Truck and Engine Manufacturers Association, on behalf of the engine builders.

Together, these organizations have committed nearly $2.7 million to pay for the matrix tests. EMAs share will be in-kind contributions of engines and parts, while the others are giving cash.

Thats not enough to cover the entire matrix though, so five engine test facilities – Afton Chemical, ExxonMobil, Intertek, Lubrizol and Southwest Research Institute – are donating the cost of running calibration tests on their engine stands. Valued at $2.3 million, this brings the total for the matrix to $5 million.

In addition to the new tests above, seven engine sequence tests will carry over from earlier diesel oil categories, for a total of nine (see table, below). Some of these go back as far as the API CG-4 category, which was introduced in 1995. The rationale for retaining these older tests is that they continue to measure pertinent oil performance properties even with new engine designs.

Not making the PC-11 test slate: Detroit Diesels proposed DD-13 scuffing wear test, because it was not showing consistent results and field correlation. After months of trying, it was removed from the category this summer – but the DD-13 still could see life as part of a proprietary Detroit Diesel oil spec, sources indicated.

Its Never Easy

Engine tests have always been a struggle to design and implement, according to Jerry Wang, OEM and industry liaison for Chevron Oronite. He has a unique perspective on engine oil development since he has been involved from both the OEM side, at Cummins Engine Co., and the additives side of the process.

Asked what triggers a new engine test or revision, Wang replied that there are all kinds of reasons, many of them not always very well justified. The drivers for engine test development remain nebulous and can be almost anything, whether reasonable or not.

Some tests arise from field issues such as the Detroit Diesel Roller Follower Wear Test; Mack T-11 for soot-loading in exhaust gas recirculation engines; and the Caterpillar 1K test for deposit control.

And some tests, Wang continued, are the result of engineering judgment, such as when Cummins anticipated higher soot production in EGR diesels with lower-phosphorus content oils, and created its ISM/ISB tests to address this. The Mack T-13 addresses the likelihood of higher oil temperatures, while its T-10 and T-12 tests targeted the potential effects of soot on ring/liner wear. The venerable Caterpillar SCOTE series – the Cat 1K, 1N, etc. – were developed because of the fact that there were differences in aluminum versus steel pistons, Wang remarked.

Field performance correlation is another trigger for test development, he pointed out, giving as examples the Chrysler oxidation and deposit test and the Sequence VID fuel economy test.

How long will an OEM work on a test before bringing it to the attention of the industry? It depends, Wang replied. Apparently, the DD-13 scuffing test is a brand-new idea that DDC ran no tests on at all before trying to create it. At the other end of the spectrum is the Cummins ISB cam cycle test, used by Cummins as an internal proving test for over a decade before Wang brought it to ASTM for wider approval and use in diesel engine oil categories.

The single most difficult part of getting an engine test into a revised category is that the test sponsor – often the OEM – is in the drivers seat and usually gets its way, Wang conceded.

Reaching the Finish Line

Once the outlines of a proposed test have been established, the test creators next must determine the exact conditions for running the test and what parameters are to be rated. Those could be measured parts such as cam lobes, lifters or bearings, as well as standard ratings of surfaces for varnish or sludge.

A new test will also need a reference oil, as a yardstick to see how it performs. Typically, two or three reference oils may be involved – a failing reference, a passing reference, or something in between. When a test needs updating, the reference oils already in place provide assurance that the test is actually repeatable and that results from the revised procedure can be compared to earlier versions.

Once reference oils are identified, they become the ward of ASTMs Test Monitoring Center in Pittsburgh, Pa. TMC takes charge of formulating and blending the reference oils, as well as distributing them to the various test laboratories. The compositions are proprietary to TMC; no additive supplier can claim them and recipients are not allowed to analyze them.

Today there are often consortia established to do the development work on engine tests since the process is time consuming and costly. The various parties to the development (API, ACC and EMA) as well as the engine laboratories share the cost, which can be quite high.

After the final procedure is developed, the reference oils selected and at least some semblance of correlation to the field is established, a test matrix must be run to make sure that different labs and engines can deliver reproducible results. Usually, that requires at least six months, if all goes well.

Matrix oils must also be selected, blended, coded and parceled out to the participating engine laboratories. These are either reference oils which are designed to evaluate the engine test itself, or a category reference oil which is a prototype formulation expected to meet all category requirements. Thats a difficult task, since the categorys performance limits cant be set until the matrix is complete and the data analyzed.

Given this lengthy process, early this summer some industry participants watching PC-11 inching its slow way to matrix testing had glumly predicted it might not be ready until late 2017. The current deadline – March 1, 2017 for first licensing – may seem a happier outcome, but EMA continues to hope licensing can begin in 2016.

Thats not totally out of the question, APIs Ferrick conceded. The timeline now is dependent on the matrix, and if it were to go efficiently, the finish date could move to an earlier time, he mused. Theres always hope we could shave some time off that March 2017 date.

Lisa Tocci contributed to this article.