Developed to meet stringent 2027 EPA emissions standards, the upcoming PC-12 oil category splits into CL-4 and FB-4 subcategories to provide enhanced thermal protection, lower emissions, and improved fuel economy.
- Regulatory Driver: The new PC-12 engine oil category launches on Jan. 1, 2027, to support next-generation diesel engines and comply with updated EPA and NOx emissions rules.
- Two Distinct Subgroups: PC-12 introduces backward-compatible CL-4 (replacing CK-4) for legacy and mixed fleets, alongside FB-4 (replacing FA-4), a low-viscosity, non-backward-compatible standard designed for model year 2027 and newer trucks.
- Lower Emissions Formulations: Both CL-4 and FB-4 feature reduced SAPS (sulfated ash, phosphorus, and sulfur) levels to withstand extreme engine heat, extend aftertreatment component life, and lower tailpipe emissions.
- Actionable Fleet Preparation: Fleet managers should compile power-unit asset profiles, coordinate with OEMs regarding duty cycles and drain intervals, and engage lubricant suppliers to establish purchasing and spec requirements.
To meet updated Environmental Protection Agency and nitrogen oxide (NOx) regulations taking effect in 2027, the latest generation of oils (PC-12) will debut Jan. 1.
Developed to support the demands of the next generation of diesel engines, the PC-12 standard has been in the works for several years. Though it is expected to help make trucks more efficient and less polluting, hesitation around this new category of oils — and what it means for your operation — is natural.
PC-12 is not anything to fear, provided you take the steps now to get your fleet ready for a new oil category. Along with understanding how this category is different from previous lubricants, now is the time for maintenance managers to start confirming backward compatibility, deciding which trucks get which oil types, and determining how preventive maintenance inspections and duty cycles will be affected.
Oil categories explained
PC-12 (Proposed Category 12) is the latest generation of oil standards dating back nearly a century. Every decade or so since the 1930s, improved engine technology has necessitated higher-quality oils to meet performance standards. Over the years, these lubricants have been engineered to run cleaner and more efficiently, resulting in reduced air pollution, improved fuel economy and extended drain intervals.
The last update to the American Petroleum Institute (API) engine oil standards was PC-11 in 2017. This change was notable for offering two subcategories for the first time. CK-4 met new standards and ensured backward compatibility with older engines, while FA-4 introduced lower-viscosity SAE 30 lubricants to the heavy-duty diesel market, allowing for enhanced performance and improved fuel economy in newer engines.
However, since the introduction of PC-11 a decade ago, emission standards have tightened even more. The new engines and emission control systems designed to meet these standards require a new class of oils to better withstand the high stress and heat of these systems. At the direction of the API, lubricant providers, engine manufacturers and other stakeholders have been jointly working on engineering PC-12 to address these needs. These new formulations will help allow for significant reductions in NOx and particulate matter, extensions in aftertreatment system life and further reductions in viscosity.
How PC-12 will change things
Just as with the PC-11 category, PC-12 will be split into two subgroups: CL-4 (PC-12A) and FB-4 (PC-12B), which will replace the current CK-4 and FA-4 groups, respectively.
The CL-4 standard will require backward compatibility with older engines to support the needs of fleets with a mix of new and aging trucks. FB-4 will be the replacement for current FA-4 engine oils and will be the standard for both new engines and the next generation. Developed for thinner-viscosity oils down to SAE 20 (and below), it is intended to deliver improved fuel economy for use only in model years 2027 and later. FB-4 will not be backward compatible.
Both CL-4 and FB-4 have been developed to use lower sulfated ash, phosphorus and sulfur (SAPS) content, drastically lowering emissions.
What to know for your fleet
There are only a few months to go until the start of 2027, so fleets should be taking the time to prepare for PC-12 now. One recommendation for every maintenance manager is to compile asset files of all power units. Check to see which models will require backward compatibility, as this will determine whether you need CL-4, FB-4 or both oil types.
Regardless, you should consult each respective original equipment manufacturer (OEM) to discuss best practices for oil drain intervals (ODIs), preventive maintenance inspections and duty cycles. In addition, reach out to your lubricant supplier to see if there are any additional steps you should be aware of.
Planning ahead and getting answers to questions today can prevent headaches, delays and other issues when changing over to PC-12 down the line. Ensure purchasing, availability and specifications are organized. The most important thing at this time is to ensure you are making the right switches for the right trucks.
Plan ahead
Oil category updates are a routine part of the industry. With proper planning, fleets should not have a difficult time transitioning to the right type for their power-unit mix, provided managers understand how PC-12 will affect preventive maintenance and other operations. Ultimately, this new oil should help keep engines running cleaner and longer — something we can all celebrate.
