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API Reports Progress on New Heavy Duty Engine Oil Categories
January 1, 2027, will be the first license date for two new heavy-duty engine oil categories, if all goes as planned.
January 8, 2026
Heavy-duty engine oils designed for 2027 diesel engines are a step closer to reality.
Credit: HDT
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January 1, 2027, will be the first license date for two new heavy-duty engine oil categories, if all goes as planned.
An update from the American Petroleum Institute said it has made significant progress in developing the new API Proposed Category 12 (PC-12) heavy-duty engine oil specification.
API PC-12 is intended to replace the current API CK-4 and FA-4 categories and align engine oil performance with 2027 engine requirements in North America.
There will continue to be two categories. If approved, API CL-4 will be the backward-compatible option for mixed fleets and existing engine designs.
API FB-4 would address lower-viscosity, fuel-efficient oils formulated for engines engineered specifically to meet the new specification.
The API Lubricants Standards Group approved three key actions that will now move to an electronic ballot:
Acceptance of the PC-12 technical requirements as outlined in the ASTM D4485 ballot with minor editorial updates
Acceptance of the PC-12 user language, which provides a high-level description of the API CL-4 and API FB-4 categories.
Acceptance of January 1, 2027, as the first license date for API Service Category CL-4 and API FB-4
Next Steps for Licensing and Industry Readiness
The API licensee portal will open several months prior to the January 1, 2027, first license date. This early-access period will allow licensees to proactively enter new API CL-4 and API FB-4 products.
An API news release said these actions mark a significant milestone toward finalizing the PC-12 specification and preparing the heavy-duty engine oil industry for next-generation performance standards.
Unresolved Technical Questions
According to a report in Lubes’nGreases last month, the committee has been dealing with some unresolved technical matters.
One is the phase-out of an engine wear test that is so old that the supply of test hardware could run out by the end of 2026, but was needed for the API CL-4 performance matrix.
There also are concerns about how backward-compatible wear protection will be validated for CL-4 oils.
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