Revisiting API-FA4 heavy duty engine oils

Truck on Highway Truck on Highway

You probably remember that in December 2016, the lubrication industry saw the introduction of two new categories of heavy-duty engine oils: API CK-4 and FA-4. CK-4 oils were intended as the replacement for the CJ-4 category oils that had been launched a decade earlier. They are backwards compatible with older engines. FA-4 oils, in contrast, are formulated specifically for newer engines designed to comply with the latest standards for fuel efficiency and greenhouse gas emissions. Because adoption of FA-4 has been slower, it’s worth revisiting what they are intended to achieve and where the industry is headed in the future.


In an earlier article, we reported that Daimler Trucks North America (DTNA) had selected Chevron for its factory fill motor oil. It is noteworthy that the oil selected, Delo® 400 ZFA SAE 10W-30, is an API FA-4 oil. DTNA’s support for API FA-4 is a clear signal of the industry trend toward more fuel-efficient oils. More and more OEMs are leveraging FA-4 oils for on-highway vehicles. Those that put a high priority on validating more fuel-efficient oils will undertake extensive computational modeling, lab-engine and field testing to determine how a lubricant will perform and, based on the results, will approve FA-4 oils for certain models of engines. Daimler, for instance, has done testing to validate FA-4 oils for vehicles built as far back as 2010. Other OEMs, however, may endorse FA-4 for engines built starting in 2017, subsequent to the category launch. And some have not yet endorsed FA-4 at all, mainly because they haven't completed validation work.


OEM interest in FA-4 oils revolves around what we call “high temp/high shear” (HTHS) viscosity, which is different from the SAE viscosity grade on an oil’s label. Lower HTHS viscosity is the main determinant of fuel economy performance. Even though, for example, a 5W-30 and a 10W-30 oil are different SAE viscosity grades, they will deliver comparable fuel economy performance, at optimal engine operating temperatures, because they are of similar HTHS viscosity. With the FA-4 category, we have seen HTHS viscosity drop to its lowest levels yet.


We expect OEMs to embrace increasingly lower HTHS viscosity oils in an effort to improve fuel economy and greenhouse gas emission performance. On the customer side, however, the situation is quite different. Fleet operators want to reduce the number of different oil grades they carry. The reality is that most fleets have a mix of trucks from different OEMs and of different ages. So, operators tend to go with an oil that can be used in as many vehicles as possible.


At Chevron, we estimate that as many as 25% of the trucks in service today could use an FA-4 oil, but because of the mixed nature of most fleets, FA-4 penetration is much lower than that. We are working with fleet operators to help them figure out ways to leverage FA-4 technology across more of their trucks and start seeing the potential benefits of improved fuel economy, while at the same time accounting for the mix of OEM brands and vehicle ages in their fleets. Lower viscosities are clearly the future, and we are committed to helping customers stay ahead of the curve.


About the Author: James Booth graduated from the University of Southampton (UK) with an undergraduate degree in Mechanical Engineering and Ph.D. in Tribology. James began his career with Chevron 10 years ago in Chevron Oronite Technology, The Netherlands, and later moved to Richmond (Ca, USA), as a formulator within Automotive Engine Oil (AEO) Product Development team. He previously held the position of Americas region AEO Product Qualification Team Leader, and vice-Chair of the American Chemistry Council Product Approval Protocol Task Group. James is currently the Commercial Sector Manager supporting Chevron’s Delo brand and other related lubricants brands.

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