API FA-4 Versus API CK-4 and API CJ-4 Versus API CI-4 Plus
API Service Category FA-4 oils are designed primarily for use with EPA10, GHG14, GHG17 and GHG21 compliant engines equipped with cooled EGR and exhaust aftertreatment devices operating on Ultra-Low Sulfur Diesel (ULSD) fuel (below 15 ppm). These oils are designed with reduced ash and phosphorous content to minimize degradation of aftertreatment devices while providing complete wear, deposit, and soot control.
API Service Category CK-4 oils are designed primarily for use with EPA07, EPA10, GHG14, GHG17 and GHG21 compliant engines equipped with cooled EGR and exhaust aftertreatment devices operating on Ultra-Low Sulfur Diesel (ULSD) fuel (below 15 ppm). These oils are designed with reduced ash and phosphorous content to minimize degradation of aftertreatment devices while providing complete wear, deposit, and soot control. API CK-4 oils may also be used in all diesel engines operating with ULSD fuel.
API Service Category CJ-4 oils are designed primarily for use with EPA07, EPA10, GHG14 and GHG17 compliant engines equipped with cooled EGR and exhaust aftertreatment devices operating on Ultra-Low Sulfur Diesel (ULSD) fuel (below 15 ppm). These oils are designed with reduced ash and phosphorous content to minimize degradation of aftertreatment devices while providing complete wear, deposit, and soot control. API CJ-4 oils may also be used in all diesel engines operating with ULSD fuel.
API Service category CI-4 PLUS oils were designed primarily for use with 2002 EPA emission compliant engines equipped with cooled EGR operating on Low Sulfur Diesel (LSD) fuel (below 500 ppm). These oils are formulated with higher ash and phosphorus content and were not intended for use in engines with aftertreatment devices. Their use in EPA07 engines may cause premature aftertreatment filter plugging.
There is a subtle but important difference between oils meeting the API CI-4 and the API CI-4 PLUS service category. Shortly after their inception, the API CI-4 category requirements were modified for improved soot handling and shear stability. An engine oil formulation that meets the modified requirements would qualify for API CI-4 PLUS. Due to their superior performance in EGR-equipped engines without aftertreatment devices, Detroit™ recommends only CI-4 PLUS oils. Detroit™ does not recommend the use of oils that only meet the CI-4 service category.