Chevron addresses PC-11 questions

Chevron has posted an ongoing PC-11 Q&A series on its Delo website, has posted an ongoing PC-11 Q&A series on its Delo website,

The switch to API CK-4 and API FA-4 oils under PC-11 has been underway since December. To help in the transition, Chevron has posted an ongoing Q&A series on its Delo website, The following is an excerpt from that series.

Q: In addition to fuel efficiency, how are these new oils protecting the engine from oxidation?

A: This is a great question, because it highlights a common misconception about the new engine oil categories. While the new specifications were certainly motivated by the need to introduce new more efficient engines and vehicles, there will also be a significant performance upgrade with the new oils in addition to the new lower viscosity grades. When engine manufacturers requested this new category back in 2011, they were clear that the new oils needed to be significantly more resistant to oxidation. That is to say they need to stand up to higher temperatures, for longer periods of time without breaking down. So, as these new products have been developed, particular attention has been given to making sure that the right combination of high quality base oils and advanced additive technology – tenants that are at the heart of Chevron Delo® with Isosyn technology – are brought together to answer the needs of the most stringent heavy-duty motor oil specification ever developed.

Q: Are you already working on PC-12?

A: Formally, no, but it isn’t too early to start thinking about the next set of requirements. New oil specs over the past 20+ years were introduced primarily due to changes in emissions regulations (first pollutants, now greenhouse gases) and there are already proposed standards that will continue to tighten over the next ten years. These tougher standards will undoubtedly require changes to engine designs that will introduce new demands on lubrication. More practically, some of the engines that are used to evaluate oils against current standards are quite outdated and long term availability of service parts is questionable. At some point, it will be prudent to part ways with historic requirements (e.g. high soot control) that just don’t seem relevant to modern engines, but that are retained for purpose of “backwards compatibility”. For these reasons, it is safe to say that.

Q: What is the biggest concern and confusion in the market surrounding PC-11?

A: According to a recent Commercial Carrier Journal (CCJ) survey, almost 48 percent of respondents are slightly to very concerned about the implementation of PC-11. Respondents’ top concerns included: the fear that lower viscosity oils will increase engine wear; possibility of needing both API CK-4 and FA-4 oils; determining the right oil for their fleet; and not being able to use the new formula in older engines and what will happen if it is used in older engines.

Q: Are CK-4 and CJ-4 compatible?

A: Yes, they are fully compatible, and there should be no concern if the two are mixed. However, full performance benefits of API CK-4 oils will only be realized when the engine is full transitioned from API CJ-4 to CK-4.

Q: What is high-temperature high sheer (HTHS) viscosity and why is it important?

A: You may not know it, but there are actually four viscosity measurements that are made to define and engine oil’s viscosity grade. The most familiar measurement is kinematic viscosity (KV) which is most commonly run at 100oC and is included in most standard used oil analysis reports. HTHS viscosity is also important, as it is run at a higher temperature (150oC) and also under stressed conditions that are more relevant to the oil’s performance in hot regions of the engine, including bearings and in the overhead. There has been a tremendous amount of testing that has shown that oils with lower HTHS viscosity can improve fuel economy. In fact, the HTHS viscosity is the primary difference between oils that will be classified as API CK-4 or API FA-4. API CK-4 oils will have HTHS viscosity of 3.5 cP or higher, while API FA-4 oils will have HTHS between 2.9 cP and 3.2 cP.

This is why it will be critically important to pay attention to not only the oil’s SAE viscosity grade, but also the API performance level (CK-4 or FA-4) to identify the product that is right for you.

Q: What are the advantages for consumers?

A: These new specifications include new performance requirements that make API CK-4 and API FA-4 significant upgrades to API CJ-4. Most notably, oils that meet the new standards will have SIGNIFICANTLY improved oxidative stability. This means that they will be formulated to provide protection against premature breakdown, even when the oil is exposed to the very high operating temperatures that are common in today’s hard working engines. In fact, one of the new oil performance tests required by the new specs runs the oil at 130oC (266oF!) for 360 hours in an engine running at full power! You can be assured that oils meeting the new standards are up to the task of protecting your engine, even under the harshest of conditions.

Q: Will this oil affect engine performance when pulling heavy loads?

A: Modern engines, as well as the specifications for the engine oils that lubricate them, are developed to address ever expanding customer needs, including the need to operate under sever duty service which can place significant stress on the oil and demand that it stand up to high temperatures when operating conditions dictate. The new API CK-4 and FA-4 specifications build off today’s standards, requiring strong wear protection, deposit control, with even more stringent requirements for protection at high operating temperatures. From that standpoint, you can be assured that the new oils will be even more robust to severe duty operation. As always, consult your owner’s manual for oil recommendations consistent with your engine make/model and service severity.

Q: How will these new oils perform in cold weather?

A: Although the new low viscosity products have been developed to improve engine and vehicle fuel economy, they also perform better at low temperature when compared to conventional SAE 15W-40 products. 10W and 5W heavy-duty engine oils must be pumpable and allow the engine to start at temperatures 5oC to 10oC colder than a 15W-40. Better low temperature fluidity means that engine oil will travel faster upon start up to the lubricated components inside the engine contributing to better wear control and engine durability.