New diesel engine oils under development

As diesel engine manufacturers strive to meet tough new emission standards for 2027, they have again called for new lubricants to help them meet the challenges, which means new standards for diesel engine oils. . The current standards established for engines entering service in 2017 — CK4 and FA4 — will be superseded.

Jeffrey Harmening, senior director of the motor oil licensing and certification system at the American Petroleum Institute, said API’s lubricants group has established a team to begin the development testing phase of the PC-12 diesel engine oil category.

“The PC-11 category produced today’s familiar CK4 and FA4 engine oils, and the PC-12 project will follow a similar path with a target date for the oils to be certified under new ratings and released for sale. by January 1, 2027,” he explains.

“In the meantime, API, OEMs and other process stakeholders should develop tests and specifications for new lubricants and adjust any existing tests used on previous categories that can be applied to the PC-12 project,” he explains.

Engine OEMs applied to API in March 2021 for an engine oil category that includes the following improvements over CK4 and FA4 lubricants:

  • Increased oxidation performance
  • Wear test capabilities
  • Lower viscosities to meet 2027 model year fuel economy standards in EPA and California Air Resources Board regulations.
  • Improved exhaust flow after-treatment capabilities.
  • Improved compatibility with the latest elastomers used in modern engine gaskets and seals.

Harmening says there will be another “C” grade oil, but whether it will follow with a “CL” moniker remains to be determined.

“Sometimes letters are skipped over in the naming of new oil categories,” he says. “Regardless of the rating letters, however, the new ‘C’ oil will be backwards compatible, so older engines rated in earlier ‘C’ grades will still be covered by the new formulation.

“Things could be different for the ‘F’ category, which will come out of the PC-12 project,” he explains.

“This grade does not need to be backwards compatible, and it remains to be seen if the FA4 oil will be retained with the new “F” oil. Currently, the new grade is considered a total replacement for FA4 due to requests lower viscosity down to XW20.

Harmening says the new “F” rating is unlikely to greatly affect agricultural equipment, since the stricter requirements for increased fuel economy are primarily aimed at road transport equipment.

However, since government regulations tend to change over time and improving fuel economy is a “top of mind” regulatory tool to reduce carbon emissions with bureaucrats on both sides of the Atlantic , those building diesels for the global agricultural market will likely be watching the trends.

This cycle of developing new categories of lubricants faces increasing challenges in the laboratory, says Harmening.

“Much of the hardware (engines and accessories) of the old Mack T-11 and Mack T-12 for testing is reaching end of life,” he says.

Engines used in test labs with specific fuels and specific oils under a variety of loads, speeds and other challenges are stripped down and inspected for wear. Before additional tests can be run, new engines and hardware must be available.

“The desire of API and other testing facilities is to find replacement tests that will satisfy the old C categories,” says Harmening.

“We may defer several tests from the PC-11 development to the PC-12 project, but we will need to assess each for the limitations imposed by the new requirements,” he says.

“The lower WX20 viscosity for on-road diesels is just part of a trend to meet new emissions requirements, and that will continue as designers try to extract as much efficiency as possible. engines by reducing internal friction and drag produced in the lubrication system.”

He says the committee will also establish protocols in the PC-12 project for Detroit Diesel’s friction test, as well as Ford’s valve train wear tests.

Harmening claims that many OEMs, distributors, additive companies and oil blenders have already met since March 2021 to plan the PC-12 project and, from January 2022, began serious work on specifications and specifications. standards.

“The 2027 deadline is aggressive, but those involved agree they will be able to deliver the category as requested,” he says.

This means that in December 2026 or New Year’s Day 2027 there will be a new category of API diesel engine oil and CK4 and FA4 will become the latest standards.

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