In December 2016, the American Petroleum Institute (API) introduced two new oil categories for modern diesel engines: CK-4 and FA-4. These oils were created to meet the needs of updated engine technology and new emission standards.

Diesel engine oil plays a big part in keeping trucks and heavy-duty vehicles running properly. Both CK-4 and FA-4 offer better performance than older oils, but they are made for slightly different uses.

What is CK-4 Oil?

CK-4 oil is designed for both new and older diesel engines. It replaces previous categories like CJ-4, CI-4, and CH-4. CK-4 offers better protection against engine wear, sludge, and oxidation. It also works well in high-temperature conditions, which is common in heavy-duty trucks and equipment. One of the best things about CK-4 is that it can be used in a wide range of engines, making it a popular choice for many fleets.

What is FA-4 Oil?

FA-4 oil is made for newer diesel engines that are built to meet strict fuel economy and emission rules. It has a lower viscosity compared to CK-4, which helps reduce fuel use and lower greenhouse gas output. However, FA-4 is not backward compatible with most older engines. This means it should only be used in engines that are built to handle this type of oil. Some engine makers have started designing engines that work well with FA-4, but it’s still not as widely used as CK-4.

Why the Two Categories Matter:

The main reason for creating both CK-4 and FA-4 was to support the changes happening in diesel engine design. As engines become more advanced, the oil used in them needs to keep up. These two categories give people more options depending on the age and type of engine they have. Using the right oil can lead to better engine life, fewer repairs, and better fuel performance.

Which One Should You Use?

Choosing between CK-4 and FA-4 depends on your engine and what the manufacturer recommends. CK-4 is often the safer choice for mixed fleets and older engines. FA-4 is more specialized and is best used when the engine is made for it. Always check your engine’s guide before switching oil types.

CK-4 and FA-4 oils were made to keep up with changes in diesel engines. While they both offer improved performance, they are built for different uses. Understanding what they are and how they work helps keep engines running smoothly.