Auto Service World
Feature   September 18, 2015   by Jobber News

C-11A vs. PC-11B What You Need To Know

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 and PC-11B 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 behaviour 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 the previous standard, 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 going forward. 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.

Preparing For The Next Heavy-Duty Engine Oil
Proposed Category 11 — or PC-11 for short — is the next heavy-duty engine oil performance category, superseding the existing API CJ-4, currently in development by the American Petroleum Institute (API). Like all new categories, PC-11 began development at the request of the Truck and Engine Manufacturers Association (EMA) in order to help better suit industry needs. PC-11 will receive an official name as it comes closer to being finalized. First licensing is currently expected in late 2016.
Q: Why is PC-11 important?
A: Recent API C (Commercial) categories have predominantly dealt with challenges presented by diesel engine changes concerning emissions of particulate matter and NOx, on which regulation has imposed strict directives in the past few decades.
PC-11, however, is driven by greenhouse gas emissions and fuel economy concerns. While increased fuel economy has been a driving concern of the passenger car industry for several years, in the world of heavy-duty trucks, this has previously been something of a side issue – overshadowed to some extent by emissions concerns, as just mentioned. This new push from regulators for higher fuel economy aligns with fleet managers’ and truck makers’ desire for more fuel-efficient vehicles.
Q: How far-reaching is PC-11?
A: API categories typically have had the most reach within North and South America, as well as Africa and Asia. Even though PC-11 is an American category in development through the API, it will have global ramifications. While Europe, for instance, has its own categories through the European Automobile Manufacturers’ Association (ACEA), many oil marketers wish to offer the same product globally – a product that meets a more comprehensive spectrum of specifications.
Q: Which vehicles are affected by PC-11?
A: PC-11 predominantly affects large diesel engines, including heavy-duty and medium-duty over-the-road vehicles. PC-11 also applies to off-highway vehicles including construction and agricultural equipment, which make up a large portion of lubricant consumers.
Q: What is different about PC-11 from past categories?
A: The EMA’s request was driven by two overarching concerns: firstly, how oil can help contribute directly to improved fuel economy; and secondly, changes in truck engines, many of which are driven by improved fuel economy, that now require oils providing more robust protection in new hardware.
One way to improve fuel economy is lower-viscosity oils. However, engine durability remains the most prominent concern for end users and requires that lower-viscosity oils meet the same high-durability standards as traditional-viscosity oils.
Because of durability concerns, there will be two branches within the PC-11 category based upon viscosity. PC-11A oils, likely to be called API CK-4, will have the same viscosity limits as those oils we know today, and will be entirely backwards-compatible with older engines.
PC-11B oils, which might be called API FA-4 or FA-1, however, will make up a split category for oils that are of a lower viscosity than current CJ-4 oils. These oils have to provide the same durability as the PC-11A thus requiring passing the same sets of tests as PC-11A, but will be recommended only for newer engines. As such, the PC-11A and PC-11B oils will be split by HTHS (High Temperature High Shear) viscosity.
Q: What are the new tests defined by PC-11?
A: While no tests have been completely defined yet, we have a good idea of what PC-11 will require of oils in order to receive the certification.
Higher Temperatures: One way to make an engine more fuel-efficient is to make it more thermally efficient, and manufacturers are increasingly exploring this route. When an engine runs at a hotter temperature, so does the oil lubricating it – and as that oil gets hotter, the thinner it becomes, making protection more challenging. Also, oxidation is more likely to occur at these higher temperatures.
Oil Aeration Test: Simply put, this test is to ensure the prevention of air building up within the oil. This is a critical test that assures an oil’s ability to resist air entrainment and foaming, so that the lubricant continues to work as a non-compressible hydraulic fluid.
Shear Stability: PC-11 will require a high shear stability of lubricants, helping them maintain the same level of protection after passing through the various parts of engines. Viscosity naturally varies, getting slightly lower or higher with the length of time an oil has been working within a given engine. New requirements will ensure that the lubricants still offer the same protection under all conditions.
Q: What does PC-11 mean for industry stakeholders?
A: PC-11 will impact varying industry stakeholders in a few ways:
• For OEMs, PC-11 will help achieve greater fuel economy and provide additional engine protection – helping OEMs keep up with regulatory pressures and in developing new, more efficient engines. Additionally, the PC-11B split category will offer a very low-viscosity option that can be utilized in modern engines.
• For oil marketers, PC-11 will offer further opportunity and incentive to differentiate. However, the further fragmentation of oil types within PC-11A and B will likely make it necessary for oil marketers to act quickly in moving away from CJ-4 oils. Past oil categories have not been this fragmented, and this sort of major change in the lubricants landscape may spur further concern for end users.
• For end users, including fleet managers and those purchasing these new oils, PC-11 will require becoming more knowledgeable than with past categories. Knowing the recommended oils for a given truck will be essential, given the split category within PC-11. An educational push on this front from many of the major oil marketers is expected. The more educated individual end users become, the more likely they are to not only purchase the correct lubricants for their fleets, but the best lubricants – meaning greater quality, durability, and longevity for fleets.
There is much work that needs to be accomplished as PC-11 draws nearer. Perhaps more than any other category in the past, PC-11 will require new testing, due in part to its split categories.
For more information on PC-11, visit

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