For the first time ever, the category is split into two:
API CK-4: backward compatible and supersedes API CJ-4 (HTHS viscosity 3.5 cP or higher)
API FA-4: for modern engines, offering greater fuel economy benefits (HTHS viscosity 2.9 - 3.2 cP)
These oils predominantly affect:
Large diesel engines, including heavy duty and medium duty over-the-road vehicles
Off-highway vehicles including construction and agricultural equipment
The new tests are oxidation and aeration, while shear stability limits are raised, providing greater protection for all engines. API FA-4 requires passing the same tests as API CK-4 with the addition of a High Temperature High Shear (HTHS) limit for lower viscosity oils.
Universal oils – those carrying API C (Commercial Vehicles) as well as API S (Gasoline Passenger Car) are based on new formulation styles with a lower phosphorus limit, protecting emission reduction systems in passenger cars.
The benefits of lubricants also having specific OEM approvals means oils have been tested to conform to their specific requirement for the specific engine. These requirements can differ from OEM to OEM, but can cover areas such as tests for:
- Daimler/Detroit Diesel’s specification involves a test to evaluate a lubricant’s ability to prevent heavy duty scuffing or adhesive wear, unique destructive wear patterns.
- Cummins’ new specifications covering API CK-4 as well as API FA-4 oil for use in their engines.
- Volvo/Mack’s new specifications include an oxidation test incorporating more stringent limits than API.
- Such higher performance lubricants with additional OEM performance claims gives greater reassurance of greater protection, durability and performance for the vehicle throughout its life.