New diesel engine oil category reaches development milestone
With the American Petroleum Institute's Lubricants Group approving the transition into the development phase of Proposed Category-12 (PC-12), the replacement process for engine oil categories CK-4 and FA-4 has kicked into high gear. It will take several years of test development and technical evaluation, but by the time the Environmental Protection Agency’s 2027 emission rules take effect, heavy-duty vehicles are expected to have even more efficient and longer lasting oil lubing their engines.
“These oils are being developed to meet the needs of the OEMs that are designing the engines that we're going to begin to see as we near 2027 and beyond,” Jeff Harmening, senior manager of API’s Engine Oil Licensing Certification System, relayed to Fleet Maintenance. “Now, the industry experts, statisticians, and engineers are now moving forward to determine what tests will be in the category.”
He added that API, the engine manufacturers, oil marketers, and additive companies will work together as a consensus body to ensure OEM-compliance to new EPA regulations—as well as California Air Resource Board heavy-duty on-highway regulations.
The result will be “even more robust engine oils than have been available to date,” Harmening said. He added that along with softening heavy-duty vehicles’ environmental impact, expected benefits should include better fuel efficiency, potential for longer oil drain intervals, and overall better total cost of ownership.
PC-12 specifics
The journey began last March when the Engine Manufacturers Association requested the Diesel Engine Oil Advisory Panel (DEOAP) improve upon the attributes of the CK-4 and FA-4 subcategories. A New Category Evaluation Team (NCET) immediately formed to evaluate the request over many months. Now the DEOAP and API Lubricant Group have authorized a New Category Development Team (NCDT) to form and standardize tests for what attributes a PC-12 oil must have and what tests will be used to determine it has them.
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According to the API, PC-12 is expected to have:
- Increased oxidation performance
- New wear test capability
- Addition of lower viscosities
- Improved aftertreatment capability
- Expansion of elastomer compatibility
The group also expects the following potential diesel engines benefits:
- Will enable of new engine technologies that are expected to experience higher brake mean effective pressure (BMEP) and customer demands, as well as accommodate anticipated regulatory requirements of extended useful life and warranty periods.
- Will support requirements for fuel economy for certain engine models.
- Will supports new elastomers used in modern engines.
The stakeholders will also consider if current engine tests Mack T-11 and T-12 will become obsolete as they likely won’t be available for PC-12.
The request for first licensing date coincides with the start date for new EPA and CARB regulations: January 1, 2027. That gives the industry about five years, which the API noted was the same for PC-11, which spawned CK-4 and FA-4.
Harmening was not sure what the new subcategories will ultimately be called, though they will be further down the alphabet, possibly CL-4 and FB-4. He did say that the replacement for CK-4 will retain backwards compatibility, while FA-4 will not, “mainly because the request includes moving down into even lighter viscosity oils—xw-20 type oils,” he explained.
The adoption of FA-4, which has a lower viscosity and advanced fuel efficiency benefits, has been underwhelming.
“FA-4 has had a very slow uptake from its inception 2016,” Harmening said. “It’s really limited to factory fills in a lot of cases at the present day, so the thinking now from all parties involved is that there will be a new ‘F’ category.”
This won’t, however, add extra work for fleets and shops servicing multiple engine types.
“That does not mean that shops might need to retain the three different oils at some point,” Harmening stressed. “That seems unlikely at this time.”
