The American Petroleum Institute (API) announced last Wednesday that it has approved two new diesel engine oil standards, API Service Categories CK-4 and FA-4. These new categories resulted from years of collaborative effort between API’s Lubricants Group, the Truck & Engine Manufacturers Association (EMA) and the American Chemistry Council (ACC).

API category CK-4 (called PC-11A during development) of higher HTHS viscosity (3.5 cP) is backwards compatible with current engines designed for oils category CJ-4. Category FA-4 (PC-11B) of lower HTHS viscosity of 2.9-3.2 cP—intended to reduce engine friction and provide fuel economy improvements—is not backward compatible with CJ-4.

“API has established engine oil quality standards since the 1940s, and these new standards are intended to help protect today and tomorrow’s diesel engines,” said Kevin Ferrick, API Senior Manager of Training and Certifications. “Our new engine oil standards are developed to protect engines, meet new government regulations, and ensure engine oil performance.”

These new service categories improve upon existing standards by providing enhanced protection against oil oxidation and protection against engine wear, particulate filter blocking, piston deposits, and degradation of low- and high-temperature properties.

API is now preparing to license engine oils against these new standards. Several items related to licensing are worth noting:

API CK-4 and FA-4 will first appear in the API Service Symbol “Donut” on December 1, 2016. This delay in licensing allows marketers time to test their new formulations and ready them for market.

Most truck manufacturers recommending API-licensed CJ-4 engine oils will likely recommend truck owners start using licensed API CK-4 oils as soon as they are available. API CK-4 oils will better protect today’s diesel engines.

API FA-4 oils, however, are different. The FA-4 standard describes certain lower viscosity oils specifically formulated for use in select high-speed four-stroke cycle diesel engines designed to meet 2017 model year on-highway greenhouse gas (GHG) emission standards. Some engine manufacturers might recommend API FA-4 oils for their previous model-year vehicles, but it is more likely that manufacturers will recommend the oils starting with the 2017 model year engines.