API CJ-4 to CK-4 Heavy Duty Engine Oil Transition

In August 2016, KLONDIKE Lubricants Corp. announced in a blog post, details on the upcoming transition in heavy duty engine oil specification. The transition relates to the new service categories launched by the American Petroleum Institute (API) called CK-4 and FA-4. These new service categories became effective on December 1st, 2016. With that date now being behind us, we look forward into the near future with how the new categories will affect the market for heavy duty engine oils.

Firstly, it’s important to understand where the heavy duty market has come from.


In 2006, mandates on heavy duty engine OEM’s were put into place to bring in reductions on greenhouse gas emissions and improvements on fuel economy averages. It was around this time that ultra-low-sulphur diesel (ULSD) was becoming prominent in North America as well. The combination of these mandates and market changes led to the creation of the API service category known as CJ-4. This standard was launched in 2006, and made mandatory as factory and service fill for all heavy duty on-road engines in North America effective 2007 model year. The CJ-4 standard has been very successful in what it was designed to do and has been the go-to fluid technology for heavy duty engines for almost 10 years.

Market Demand for New API Service Categories

Over the course of the last few years, heavy duty engine OEM’s have been under considerable pressure to offer engines that are more durable, more fuel efficient, and produce less emissions than ever before. New legislative mandates along with exhaust after-treatment system and engine hardware changes, all work together to create harsher conditions in which the lubricant is operating, and has its effects on the overall performance of the oil. Part of the solution to this challenge is through improvements in lubricant technology, and thus the concept of two new service categories was born. And while the goals of the different categories are alike, they are different in the way they accomplish the overall outcome.


API CK-4 is designed as a direct successor and replacement for the incumbent CJ-4 fluid technology. API CK-4 fluids are fully backwards compatible and supersede CJ-4 and previous service categories. API CK-4 fluids offer improvements in oxidation resistance, viscosity shear stability, and aeration control over the previous fluid technologies. CK-4 fluids also have a HTHS (high temperature high shear) viscosity of 3.5 cP or higher, similar to CJ-4 fluids. This category includes SAE XW-30 and XW-40 viscosity grades.


API FA-4 is designed for new engine technologies and is not backwards compatible to previous categories. FA-4 brings all the same fluid technology improvements as CK-4, but with reduced HTHS viscosity of 2.9 – 3.2 cP. Lower HTHS viscosity offers further reduction in internal friction and thus, supports fuel economy improvement potential. This category has a maximum viscosity of SAE XW-30.

OEM Spec Numbers for API CK-4 and API FA-4

In general, the heavy duty engine manufacturers in North America are embracing the new engine oil technology, as they have been involved in its development and testing. Most have presented their own specification details and issued spec numbers. At the time of this writing, the following is known from various engine manufacturers:

Engine Manufacturer Specification for API CK-4 Oils Specification for API FA-4 Oils
Cummins CES 20086 CES 20087
Detroit Diesel DFS 93K222 DFS 93K223
Volvo / Mack / Renault VDS-4.5/EOS-4.5/RLD-4 Not yet announced
Ford WSS-M2C171-F1 None


Will API FA-4 Fit into the Market?

There remains some deliberation in the industry of where API FA-4 oils will fit into the market. Some OEM’s are still testing various FA-4 technologies on their specific equipment to satisfy their engineering departments regarding concerns about premature wear. This perception has had to be constantly proven with each OEM as the low HTHS viscosity reduces the lubricant film on metal surfaces to levels previously thought to be unsafe. However, engines designed with this in mind can take advantage of the reduced internal friction offered by the lower HTHS viscosity and the combined benefit is the most fuel efficient engine designs the heavy duty industry has ever seen. These specific hardware design changes are what limits the backwards compatibility of FA-4 to previous generation engine models. As the number of FA-4 specific engines on the market is still very limited, the market demand for FA-4 fluids will remain low for the near future.

KLONDIKE CJ-4 to CK-4 Heavy Duty Engine Oil Transition

What we do know is that API CK-4 fluid technology presents a natural and beneficial transition from CJ-4 and that the heavy duty market is embracing this change.

KLONDIKE Lubricants Corp. is transitioning all its current CJ-4 products to CK-4 technology as a running change over. Watch for new packaging and future heavy duty offerings in our inclusive heavy duty engine oil family!

KLONDIKE Lubricants Corporation is an independent Canadian company with oils and lubricants distribution facilities in:
Greater Vancouver, BC ● Edmonton, AB ● Winnipeg, MB ● Greater Toronto, ON ● Moncton, NB