New API specifications CK-4 and FA-4 for heavy duty into effect from Dec. 1st, 2016

Wolf Lubricants, engine oil, motor oil, heavy duty, general

The heavy-duty diesel engine oil market has two new specifications, CK-4 and FA-4. The new categories represent a significant upgrade, but are quite different in their application. Find out more here.

New specifications come into effect: API CK-4 and FA-4

Yes, 2016 is over, but there is one more change to be accounted for. As of December 1st, new API specifications for the new category 11 oils (PC-11) came into effect. 

The new specs will replace the CJ-4 classification with a split category for High Temperature High Shear viscosity grades (HTHS). With the split in categories, it is important to take note of the differences between the two.

What’s the difference between API CK-4 and FA-4?

For use in heavy-duty diesel engines, the new CK-4 oils will affect oil choice for both older and newer models of large diesel engines, including those used in non-highway applications such as agriculture or construction. 

Though both oils can be used in older and newer engines, CK-4 oils are specifically designed for backwards compatibility and are designed for high HTHS engines (at least 3.5 cP), where FA-4 oils are designed for newer and modern engines (between 2.9-3.2 cP).

Owners and oil suppliers should be up to date on the manufacturers’ specifications for specific engines, but a good rule of thumb is to think of FA-4 first for newer engines.

The differences between the two specifications are noted through their labelling “donuts”.

API developed a special label to differentiate the FA-4 specification from the CK-4 one. They introduced a red shaded part in the donut for the FA-4:

Why the change?

The old category for engine oil was sufficient for its time, but new regulations and consumer demands for better fuel economy and engine durability sparked the change. The change is the culmination of almost nine years of developing the new standards and was designed to allow marketers to do their due diligence with testing the new capabilities of the classifications. 

The update notes the different needs of newer and older model diesel engines, respectively. 

The CK-4 oils, a significant improvement over CJ-4, will provide extensive protection over a range of factors such as oxidation, shear stability, engine wear, and deposits. It is designed for engines that use diesel fuel with a sulphur content up to 500ppm. The FA-4 oils are designed to meet the needs of 2017 model engines with the stricter greenhouse gas emissions requirements and use fuels with sulphur content below 15ppm. 

This split is made to meet the emissions control needs of newer engine designs and after treatment systems. If you are using fuel applications above 15ppm sulphur, FA-4 oils are not the right choice.

As always, check manufacturers’ guides when assessing the needs of your engine oil.


  • CK-4 oils to replace CJ-4 oils with backwards compatibility
  • FA-4 oils to replace CJ-4 oils without specific backwards compatibility
  • Significant improvements in oxidation resistance, aeration, and shear stability and fuel economy
  • Given the split in specifications, it is important to know the differences between the two new categories