API CK-4 and FA-4 Engine Oil Requirements and Chemistry
by Michael D. Holloway, MLT I, OMA I, CLS
Manager Strategic Accounts & External Training, Tribology

There has been many articles and presentations on the new API engine oil classification that will be introduced in 2017. One of the main concerns raised by end-users has been compatibility. The new diesel engine oil classification API CK-4 is backward compatible with CJ-4 and older oils and the FA-4 will not be backward compatible. This is due to the new engine oil chemistry that will be used. These additives include anti­oxidants, detergents, dispersants, anti-wear compounds, friction modifiers, antifoam, and viscosity modifiers in the form of organic compounds or organometallic compounds. In the past, in order for oils to meet the API classification requirements, they must have been compatible with other oils of the same class and be backward compatible with previous classifications. This is true for the new CK-4 classification. The API CK-4 classification is for use in 2017 high-speed four-stroke cycle diesel engines and Tier 4 non-road exhaust emission standards as well as for previous model year diesel engines.

The other new classification, the FA-4 is being required for new engines (2017+) that require a lower viscosity. The reduced viscosity also has several other characteristics that will help drive down emissions and conform with the fuel economy standards being applied to new diesel engines. The API FA-4 classification is 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. These oils are blended to a high temperature high shear (HTHS) viscosity range of 2.9cP-3.2cP at 150C to assist in reducing emissions. These oils are not interchangeable or backward compatible with other oils primarily due to the fact that they have a viscosity requirement that is not in the same range requirements as other API oil classifications.

In order to meet the new requirements, the oils are being formulated with polymers that exhibit a higher shear resistance. This will allow the oils to stay within the required viscosity requirement and not be sheared down. Additionally, these oils must have an increase in oxidation resistance due to increased temperatures, improved anti-wear performance and anti-foaming / anti-aeration performance. While the introduction of these new API classifications will help reduce emissions and increase fuel economy, there is still a need to understand the optimal change interval, potential cross-contamination as well as diagnosing any wear or contamination problems before they become costly. ALS can help in both cases. Contact your local lab to find out more of how ALS can help drive down parts replacements and downtime.