At the December ASTM meetings, industry put the final touches on PC-12, the new heavy-duty category, setting first allowable use for Jan. 1, 2027. Three ballots were sent to the American Petroleum Institute’s Lubricants Standards group, seeking final approval for the first allowable use date mentioned above; to update PC-12’s categories, API CL-4 and API FB-4, into ASTM D4485; and to adopt new API user language.
These ballots were expected to be approved by the end of January 2026. Then it should be smooth sailing to a successful launch for the first upgrade since the December 2016 introduction of PC-11 under the API CK-4 and FA-4 banners. A few unknowns do remain, however, for PC-12.
This performance upgrade had some key challenges. Several key tests from the prior category needed to be replaced or would not be supported. Some tests were found by the Category Life Oversite Group to be redundant, helping define which tests would no longer be needed. Mack-Volvo, which has sponsored key API industry engine tests in the past, decided not to sponsor a replacement for the Mack T-11. Industry then developed the new ISB viscosity test to measure soot induced viscosity increase for the category.
Another key challenge was how to replace the Mack T-12 test for ringer and liner wear. This became a major problem as the original test sponsor tried to include ring and liner wear into the Volvo T-13 oxidation test but failed to do that for PC-11. Eventually industry found that the Mack T-12 was redundant to the ISB camshaft lobe wear parameter after an extensive data review by industry stakeholders. It should be noted Volvo will continue to sponsor the Volvo T-13.
Industry officially added the Daimler DD13 Scuff Test, which was not ready when PC-11 was approved but has been required by Daimler Truck since 2017 as part of its OEM specification. Some other EMA test sponsors would no longer ensure long term availability of the Cat 1N test for high-temperature protection from piston deposits, ring sticking and scuffing or the GM roller follower wear test. The former was determined to be redundant to the Cat C-13, while the latter was found redundant to the Cummins ISB test for tappet wear. Many had already felt the RFWT could have been dropped from PC-11, so it is long overdue for this test to be dropped.
Besides the new engine tests, there were several other key changes for PC-12. Most notable is the addition of new viscosity grades that would allow lower viscosity SAE 0W-20 and 5W-20 grades into the market with a minimum high-temperature, high-shear viscosity of 2.6 centiPoise vs. the 2.9 cP allowed by API FA-4 for PC-11B. These new grades are generally not backwards serviceable to older engines although some OEMs may allow some limited back serviceability. Another major change concerned the lowering of key chemical limits, including phosphorus from 1,200 parts per million max to 800 ppm, sulfated ash from 1% to 0.9% max and sulfur from 0.4% to 0.3%. Elastomer seal material was also updated, and the Volvo T-13 test limits were tightened.
Despite all that has been accomplished to date, work is far from complete as industry moves from the technical demonstration and final limit phase to oil qualification and the mandatory waiting period. While it is expected that these new API oils will be available before first allowable use, there are some unknowns for both marketers and additive companies.
“Introducing new API CL-4 and FB-4 oils is not as simple as just passing the new API specifications,” said Shawn Whitacre, principal engineer for lubricants technology at Chevron and chairman of the Heavy-Duty Diesel Engine Oil Classification Panel. “Premium heavy-duty engine oils carry both OEM and ACEA claims in addition to the API requirements. While ACEA standards are known along with some OEM specifications, other OEMs have not introduced their final specifications and plans regarding these next generation engine oils.”
Industry also expanded base oil interchange and viscosity grade read-across requirements that will simplify deployment especially for general market oils. This allows formulators to increase Group III content without having to run procedures such as the Detroit Diesel DD13 scuffing and ISB viscosity tests in multiple stocks. Rules make it easier to also support full Synthetic SAE 10W-30 and 15W-40, but deploying 5W-XX and 0W-XX products remain complex undertakings for the industry.
“Given that the category development timeline remained on schedule and limits have been agreed to, I am confident that we’ll start seeing oils capable of meeting the new standards later this year, in time for them to be available to customers taking delivery of the latest model year hardware,” Whitacre said. “As we saw in previous categories, it may take a bit longer for some of the more challenging viscosity grades.”
Many factors determine the speed and introduction of new products during the mandatory one-year waiting period once a new category is formally approved. Additive companies must run many expensive engine test programs, both for the general market and for lube marketers demanding exclusive formulations. Engine test capacity is another factor when so many stakeholders are running programs in parallel, and this is true both for API tests, several European tests for ACEA and for tests included in key OEM approvals. Work and investments will be appropriately prioritized, so only time will tell what happens for PC-12. Since 10W-30 and 15W-40 represent roughly 90% of sales, those products should get priority. While it is expected that some SAE 5W-20 oils will be ready for OEM factory fill needs, widespread introduction may not happen for quite some time, especially given that factory fill needs are not completely clear at this time.
“The market is slowly moving to lower viscosity grades, with SAE 10W-30 now being very important,” said Danny Pridemore, industry liaison manager for Infineum. “Adoption of XW-20 viscosity grades will be driven by OEM engine oil recommendations, though headwinds remain as fleet managers desire to have one oil in their multi-engine fleet maintenance shops. This helps to avoid misapplication, and some may question the capability of those viscosity grades to protect engines. While oil marketers will offer XW-20 products in their portfolios, long-term forecasts suggest these viscosity grades will account for less than 3% of the North American market by 2034.”
Replacements for SAE 5W-30 and 5W-40s may also take some time due to cost and complexity of these premium SAE grades. From my experience, fully licensable SAE 0W products may not be seen for a long time!
Market wise, we have seen growth of SAE 10W-30 and 15W-40 full synthetic products since the introduction of API CK-4. Deployment should be a little easier going forward but still require added investment. As a reminder, terms like synthetic blend and full synthetic are marketing terms. It will take time for marketers to support value-added claims, such as extended drain intervals, to promote sales of these products above conventional offerings. Deciding which base stocks fall into the synthetic category is also a marketer decision — especially for synthetic blends, which raise the question of how much synthetic base stock is needed to make that claim. It’s clear additive companies and marketers will be busy in 2026 and likely into 2027 and beyond
Two other important issues remain. At the December meetings there was some concern, raised by the Engine Manufacturers Association, regarding API user language. Behind the scenes there seems to be some reluctance from off-road diesel OEMs about further tightening phosphorus limits. PC-11 had options with phosphorus limits ranging from 800 ppm to about 1,100 ppm, but PC-12 has an 800 ppm maximum across the board.
This is likely not a concern for on-road use, but off-road end users may be more reluctant. At the outset of PC-12 planning, many off-road OEMs were happy to continue with CK-4 engine oils. It is noted that the new oils have been deemed back serviceable to API CK-4 and older performance.
The second issue concerns actual demand for new FB-4 oils. API FA-4 demand has been extremely limited, and if there was reluctance to use slightly lower viscosity FA-4 oils, how will users respond to even lower SAE 5W-20 oils. In 2016 my crystal ball predicted very little demand for FA-4 well into the next decade and some said I overestimated. I am making the same prediction for API FB-4 lubricants, especially 5W-20, without significant OEM promotion. It may still be many years before we see even low-viscosity XW-30 oils as fleet managers stick with SAE 10W-30 API CL-4! Ford announced at ASTM that it will not use the new API specifications. As with PC-11, it will continue to only recommend products meeting Ford service fill specifications.
The final issue is that since older engines still have some remaining life, the Category Life Oversite Group will also have its work set out to ensure that industry can maintain older heavy-duty quality levels. This is particularly true for API CH-4 and CI-4, which represent most of the heavy-duty products sold around the world. I expect the categories focused on North America to largely be replaced, including CJ-4 and CK-4, although CK-4, with its higher phosphorus limits could hang around if off road OEMs demand it.
“Once again, API’s new category development process has successfully delivered a new performance heavy-duty diesel engine oil standard for next generation engine needs,” Pridemore said. “The process works and is flexible enough to handle the challenges that inevitably arise for every new category development. The next generation of industry leaders faced a steep learning curve; for some, it was their first new category development. Working together, these colleagues ensured successful delivery of PC-12.”
As an industry veteran myself, I have seen many successful heavy-duty upgrades and have personally formulated products as far back as API CD or CF-4. I became active in industry specification development activities in the mid-1990s for PC-6 — a long time ago! Throughout most of my career, these upgrades were led by the late Jim McGeehan of Chevron and Greg Shank of Mack, with major contributions from Steve Kennedy of ExxonMobil and the late Pat Fetterman of Infineum.
For PC-12 the torch was successfully passed to a new generation of leaders including Chevron’s Whitacre, Karin Haumann of Shell, Mike Alessi of ExxonMobil and David Brass of Infineum to name a few. On the EMA side, several colleagues stepped up to support the category including Hind Abi-Akar before she retired and replaced Greg. Much hard work well done, and my apologies to the many who I did not name who played important roles through the years.
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. Contact him at sghaffn2015@gmail.com or 908-672-8012.