The main drivers for change of specifications are boosting fuel economy while maintaining durability of the engine running at hotter temperatures. The trend of fuel economy comes from the end-used striving for lower operation costs but also from more and more restricted green house gas (GHG) emissions regulation. Back in 2011, Environmental Protection Agency (EPA), with other American agencies, set up a new Heavy Duty National Program to establish new rules to reduce the GHG emissions and reduce fuel consumption. In order to fulfill these new requirements, new engine designs had to be introduced and started to look at lower viscosity lubricants to enhance the fuel economy. Engine Manufacturer Association (EMA) made a formal request to the API for a new commercial engine oil category. Before a final name could be decided, the new category has been called Proposed Category 11, PC-11.
PC-11 specification will end the easiness of API. Indeed, when a new specification is issued, it is then backward compatible with the older ones. For example, if a vehicle request a CH-4 and there is only lubricant with API CJ-4 available, it can be used. The new specifications PC-11 will divided in two categories:
- 11- a: API CK-4, which is the direct replacement of CJ-4.
- 11-b: complete new category, called FA-4
Both categories have enhanced durability and provide better Fuel economy compare to CJ-4.
CK-4 is designed to be a more robust CJ-4 with viscosity grades such as 15W/40, 10W/30 and 5W/40 and high HTHS. CK-4 oils will be recommended by every OEM for on and off-road applications.
FA-4 would be more a robust CJ-4 at lower viscosity. They will be mainly 10W30 and 5W30 grades, with low HTHS. These oils, though with a lower viscosity, are designed to fulfil the constraining durability requirements. They are designed only for on-road applications and will have to be used only where they are recommended by OEMs.
consequence, OEM are starting to issue new specifications for API CK-4 and/or
information, you can consult the official website of API: