Oil marketer engine test labs are likely to get a lot noisier later this year as technicians there begin evaluating various new diesel engine oil formulations for a projected new category release in 2027.
Today’s familiar American Petroleum Institute heavy-duty engine oil categories CK4 and FA4 will be stepping down Jan. 1, 2027 to make way for yet-to-be labeled lubricants being designed specifically to meet more stringent EPA targets and to help engine manufacturers develop cleaner, more efficient diesel engines.
When the Truck and Engine Manufacturer’s Assn. (EMA) approached API’s Heavy-Duty Engine Oil Classification Advisory Panel in 2021 it was seeking an oil category including the following improvements over the current CK4 and FA4 lubricants:
- Increased oxidation performance
- Improved wear test capabilities
- Lower viscosities to meet 2027 model year fuel economy standards in EPA and California Air Resources Board regulations
- Improved exhaust stream after-treatment capabilities
- Improved compatibility with the latest elastomers used in modern engine seals and gaskets
At the time, API senior manager of the Engine Oil Licensing and Certification System, Jeffrey Harmening, indicated there would be another “C” category oil, but noted it was yet to be determined if it will follow the “CK” moniker with a “CL” replacement.
He explained sometimes there are skips in new category names, but assured users the new “C” category will be backward compatible, so engines rated under the earlier “C” categories will still be covered with the new formulation — currently under development in API’s PC-12 project.
We recently visited with Bill O’Ryan, API’s senior manager of its Engine Oil Licensing and Certification System, and Karin Haumann, Shell Lubricants OEM Tech Services manager and chair of API’s New Category Development team, concerning the progress of the PC-12 project.
Haumann says the project is continuing the higher viscosity “C” and the lower viscosity “F” classification but, like Harmening, has no promises of how the lower-viscosity oils will be labeled in their final form.
“The engine manufacturers are now facing requirements to have a longer useful life and warranty periods for both engines and after-treatment systems, and, as always, they are looking to meet those emission goals with improved fuel economy,” she explains. “They’ve asked that we examine some of the limits on chemistries we use that can help extend the life of their after-treatment systems, and they are looking for increased oxidation stability.”
Better oxidation stability would possibly improve drain intervals and could provide a path to increasing engine operating temperatures for improved efficiency and an additional avenue to control viscosity.
“I think it’s a goal of the OEMs to be able to have that opportunity to offer extended oil drain intervals to help the total cost of ownership for their customers,” she notes.
Haumann says most of 2023 was spent “ironing out what tests are going to be included to make certain we maintain backward compatibility and set all of the performance targets new oil formulations must meet.”
PC-12 will include the Detroit Diesel DD13 scuffing test for both the C and F subcategories, as well as Ford’s valve-train wear tests.
O’Ryan says API is replacing the Mack T11 test with the Cummins ISB viscosity test with PC-12.
“Then, because we’re looking at the lighter-viscosity grades in the new F category, xW-20s, for instance, there will be some new reference oils in all of the engine tests in PC-12 development,” he explains.
Haumann says PC-12 is a collaborative effort between EMA and additive companies, as well as the oil marketers.
“We don’t unilaterally decide upon targets. We all know we must have targets we can meet, so there is much collaboration at every step of this process,” she explains. “Once we have all the targets set, we can then begin working to develop candidate lubricants for testing — from which will emerge the products end users will see on the shelves in 2027.”
She also notes the new category will carry “future proofing” in the fact it will include xW-20, 0W-25, W-20 ranges. While there may not be any market demand in early 2027 for those grades, API is including them because the category is expected to last through 2040. During that time it’s conceivable some engine manufacturers may turn to those grades to keep their products in compliance, and such pre-certification would preclude having to go through the lengthy new-category development process again.
Both Haumann and O’Ryan say there are a few more proof-of-test hurdles to be cleared, but both believe engine labs will be humming with new candidate lubricants by the end of 2024. The result will be new category classifications for whatever diesel engine you may be building or buying the day after New Year’s Day 2027.
