The upcoming PC-11 category will be split between backwards-compatible and new, lower viscosity lubricants—and it’s a major step forward for the marketplace.

The decision to split the upcoming PC-11 heavy duty engine oil category is a crucial one, driven by a shifting global focus toward increased efficiency in all trucks. Where past categories revolved around emissions reduction, PC-11 contributes to better fuel economy—a goal shared by all industry stakeholders.

By distinguishing PC-11A (now known as CK-4) and PC-11B (now known as FA-4) lubricants, the new category defines both backwards-compatible lubricants for existing trucks and new, lower viscosity lubricants for modern hardware. PC-11B marries new engine designs with lower viscosity lubricants while PC-11A accounts for the millions of older-model trucks on the road today, ensuring that hardware and lubricant technology continue to evolve in tandem.

Key Differences

PC-11A and PC-11B lubricants are distinguished by their high temperature high shear (HTHS) viscosity rates; PC-11A lubricants are defined as those with a minimum 3.5 HTHS, while PC-11B lubricants fall between 2.9 and 3.2 HTHS.

Because lubricants exist in a hot and turbulent engine environment, HTHS viscosity measurements more accurately mimic the behavior of an engine, and better correlate with potential fuel economy benefits. And as viscosity grades continue to trend lower, it’s important that the industry becomes familiar with HTHS, what it means and how it is used.

PC-11A is designed as a broad fit for existing trucks, and requires higher levels of protection and performance for end users than what was established by API CJ-4. While lubricants classified under PC-11A are backwards compatible, this category nevertheless represents a major step up for performance, and will require significant investment to meet the new requirements.

PC-11A lubricants will correlate with familiar kinematic viscosity grades as defined within API CJ-4, such as 15W-40, 10W-30, 5W-30, and so on. Once final, PC-11A is expected to be called API CK-4 in keeping with traditional nomenclature of the category.

PC-11B reflects the increasing adoption of lower viscosity lubricants in modern engine hardware, and will standardize these advanced products while maintaining protection and durability. These lubricants will mostly correspond with the kinematic viscosities 10W-30 and 5W-30, but will be referenced by their lower HTHS viscosity, to be distinguished from PC-11A.

Because of their lower viscosities, PC-11B lubricants will primarily contribute to greater fuel economy gains in engines specifically designed to take advantage of lower viscosity lubricants; PC-11B lubricants may not be broadly backwards compatible. Once final, PC-11B is anticipated to be named API FA-4.

Performance Requirements

It is well established that lower viscosities contribute to fuel economy gains, but it becomes more challenging to maintain protective benefits as viscosity goes lower. To ensure this protection and durability, all PC-11 lubricants, through each split category, will be subjected to the same rigorous performance testing.

As mentioned, PC-11 sets considerably higher performance limits than API CJ-4 for all lubricants, and includes two new tests: the CAT C13 Aeration test and the Mack T13 oxidation test. Development of new oils that meet the performance requirements standardized by PC-11A and PC-11B will require significant investment, formulation expertise and advanced additive chemistry. Although both categories require the same set of performance requirements, it is expected that PC-11B oils will be challenged beyond that of PC-11A because they will need to demonstrate the same level of protective benefits but at a lower viscosity level.


PC-11 lubricants are expected to be available in the marketplace before the end of 2016 (first licensing is expected to be December 1, 2016) and the category’s uncompromising nature is important as we look even further beyond that date. Lower viscosities are here to stay, and while fuel economy gains are a must in today’s marketplace, they must be balanced with durability and protection to achieve total efficiency.

PC-11B, particularly, helps deliver fuel efficient, lower viscosity lubricants that can stand up to the hotter, higher-pressure conditions of modern engine hardware. Additive lubricant technology continues to advance, allowing for thinner and more fuel efficient oils that provide excellent protective benefits. Modern heavy-duty hardware can take full advantage of these lower viscosity lubricants, and that benefits everyone—federal regulators, OEMs and fleet managers.

Lubrizol has invested its resources in developing the advanced additive chemistry necessary for unmatched fuel economy gains without sacrificing robustness and protection, all backed by unmatched real-world testing capabilities. Through its involvement in the development of PC-11, Lubrizol has the knowledge and experience to bring forward-looking solutions to market, to help its customers achieve success under the new category and beyond.

For more information about PC-11, read our PC-11: Q&A and visit our PC-11 section

To discuss how Lubrizol’s expertise can grow your PC-11 business, contact your Account Manager.