CARB is also working on other strategies, such as lengthening the useful life and engine warranty periods from 435,000 miles today to 1 million miles or more. OEMs interest in the effects of certain chemicals used in lubricating oils, which can contribute to the reduction of useful life of the after-treatment systems, may drive a renewed focus on the current limits of phosphorous, sulfur and sulfated ash, he added.

The twin newest heavy-duty engine oil service categories, API CK-4 and FA-4, were introduced to the market on Dec. 1, 2016. While CK-4 oils are backward compatible with older service categories and engines, FA-4 oils are lighter viscosity and are meant for use in 2017 model year and newer engines.

The second phase of the United States Environmental Protection Agency and the National Highway Traffic Safety Administrations joint Greenhouse Gas Emissions and Fuel Efficiency Standards for Medium- and Heavy-duty Engines and Vehicles will become effective between model years 2021 and 2027.

Unlike Phase 1, Phase 2 of the rule includes technology-advancing standards, or standards that rely not only on currently available technologies but also on utilization of technologies now under development or not yet widely deployed.

Further, in response to a petition from 20 state and local governments across the country, the EPA announced plans to clamp down on nitrous oxide emissions (a precursor to ground-level ozone) from heavy-duty on-highway vehicles, beginning with model year 2024. However, according to a July 18, 2018, report from the Congressional Research Service, delays in developing the standards are expected under the current administration.

When will PC-12 get here?

At another ASTM meeting in June, DEOAP co-chair and Caterpillar fluids technical expert Hind Abi-Akar reported that EMA will have a clearer picture of engine manufacturers needs regarding engine oil standards by December, when the next committee meeting is scheduled.

Tia Sutton, who replaced Gault when he retired earlier this year, noted that EMA is gathering information from engine manufacturers to ensure that needs are understood, including timing. It is never too early to start work, considering how long it takes to develop new tests and specifications, she said.

Shawn Whitacre, chairman of the API Heavy-duty Engine Oil Classification Panel, acknowledged that greenhouse gas regulations are the driving force behind on-highway engine development. Since fuel economy improvement is the key lever to meeting these standards, it is clear that lower-viscosity oils will be a part of the solution.

However, the benefits of the API FA-4 category, which we introduced in late 2016, havent been fully leveraged. EMA hinted that their use could become a more significant part of the strategy during the interim part of the phase-in and that 2027 could represent the point where the next step-change is required, he reported.

Dan Arcy, of Shell Global Solutions and co-chair of DEOAP, noted that EMA has not officially requested a new category, so there is currently no real target for PC-12 introduction. New regulations would imply that new technology is unlikely to be needed prior to 2024, but probably no later than 2027. While this may seem far away, engine test development and availability for the next category is critical, he said.

The availability of our test platforms that underpin all of the current licensable categories is another key consideration, Whitacre added. Engines and the parts to rebuild them wont be available forever, and the industry is taking a closer look at how that could affect our ability to test against todays standards. While that on its own shouldnt drive the adoption of a new performance spec, it certainly affects how and when the industry can do so.

Updates on all available diesel engine tests were presented at the ASTM meetings, and currently it appears that tests will be available until at least 2024, barring unforeseen circumstances.

Arcy emphasized that developing appropriate engine tests is indispensable to successfully deploying new engine oil standards. He noted that the Volvo T-13 test could be used not only for oxidation performance, as it is in the current category, but also to ensure protection against ring and liner wear. This would eliminate the expensive Mack T-12 test for wear performance.

The potential also exists for the Ford 6.7-liter valve train wear test, introduced in 2017, and the Detroit DD13 engine scuffing test, which was updated in 2018, to replace or eliminate older wear tests.

However, older API service category oils are still commonplace in some regions. The [heavy-duty diesel] lubricant industry is taking a close look at the current legacy tests to determine how long they will last and for how long they need to be supported. Clearly, the OEMs are facing more challenges in continuing to support these tests, Infineums Musmacher said.

For example, Volvo will be limiting their continued support of the Mack T-12 and Mack T-11 tests due to their limited applicability to current Volvo and Mack engines, although they will not oppose efforts by others to continue to keep these tests in oil categories if the industry feels they are needed, he continued.

What will PC-12 look like?

Whitacre pointed out that API CK-4 and FA-4 introduced new oxidation stability, shear stability and aeration control requirements, and that some OEM specifications are even more stringent for oxidation stability. That is clearly an area of emphasis, he said.

In response to emerging requirements from CARB to extend the useful life of emission control systems, we may see additional scrutiny on the chemical box that defines allowable levels of sulfated ash, sulfur and phosphorus in lube oils, he continued. However, todays on-highway engines dont generate the same levels of soot-a reason for reducing SAPS in oils-as most of the diesel engine wear tests in current categories. EMA has said it will review this discrepancy.

Whitacre also expects new or different ways to evaluate wear control.

EMA pointed to lower viscosities for future oils, even beyond the current 2.9 centi­poise high-temperature high-shear viscosity required by API FA-4. Lower SAE viscosity grades may also be coming. There are multiple OEMs in the European Union that are already using oils below 2.9 cP HTHS as factory fill today, said Whitacre. These are largely managed via their own specifications, rather than an industry standard, though.

Arcy added that API CK-4 and FA-4 technology is very robust-the best he has seen by far in his career-and would be strong enough to enable lower SAE grades. He also noted that European OEMs Scania and Iveco use SAE 0W-20 for factory fill, and he believes API FA-4 could be expanded with a supplemental category to allow for oils as low as 2.6 cP HTHS using the current specification before PC-12 is even needed.

According to Musmacher, Volvo said in April that the company is working on its next specification, Volvo VDS-5, which will be based on API FA-4 and Europes ACEA F11 standards, but limited to the SAE 5W-30 viscosity grade. These oils are expected to provide 0.5 percent fuel economy improvement and 50 percent longer oil drain intervals over current Volvo VDS-4.5 oils when they are introduced in North America in December.

For North America, SAE 15W-40 has peaked and will decline, Musmacher said. SAE 10W-30 will see the most significant growth, and by 2025, greater than 50 percent of the on-highway lubricants will be SAE 10W-30. Its mostly CK-4 today, but FA-4 adoption will be a next step. GHG Phase 2 legislation will drive greater use of API FA-4 through the medium term, while 20-weight oils may start to appear at the end of the next decade.

Whitacre pointed out that off-highway equipment is also a significant portion of global lubricant demand. SAE 15W-40 API CK-4 oils are generally preferred for such applications, and off-road OEMs have not indicated when they may adopt API FA-4. For the foreseeable future, I think that the scenario will remain fragmented, and there wont be a one-size-fits-all grade for all products in all markets, he said.

Today,SAE 10W-30 CK-4 is becoming the grade that balances protection and improved fuel economy and can handle both old and new engines, not to mention many off-road lubricant applications, said Arcy.

History suggests that wholesale changes to new viscosity grades take time, Whitacre observed. As we saw with the transition from SAE 15W-40 to SAE 10W-30, OEM recommendations play a big role in the adoption rate. As it stands today, not all OEMs selling engines in North America allow API FA-4 oils, and some that do, dont allow it in older engines. That is a big hurdle for large mixed fleets that often run hardware from multiple OEMs, including some older equipment. As those constraints ease, and as the big fleets realize the benefits, I expect the adoption will increase significantly.

Steve Haffner is president of SGH Consulting LLC. He has over 40 years of experience in the chemical industry, primarily with Exxon Chemicals Paramins and Infineum USA. He specializes in engine oil formulation and marketing. Contact him at sghaffn2015@gmail.com or 908-672-8012.