Editor’s Note: Our friends over at Driven Racing Oil produced this technical bulletin alerting consumers to the possibility of increased wear issues related to the new CK-4 diesel oil formulation. To find Driven Racing Oil products at your nearest Parts Pro™ affiliate, see our Store Locator.
Diesel engine oil makers recently changed from the decade-old CJ-4 formulation to the new CK-4 formulation. While intended to be an upgrade, the new CK-4 formulation has been met with resistance and even an outright “do not use” warning from Ford Motor Company.
Just before the new CK-4 specification went into effect in December 2016, Ford Motor Company issued a service bulletin stating that Ford 6.7L diesel engines should not use the new oil, citing identified wear issues. In fact, Ford also issued a new oil specification closely aligned with the previous CJ-4 formulation and called for its use in Ford 6.7L diesel engines. So what’s going on here?
Previous API diesel oil specifications, like CJ-4, had to pass the ASTM Sequence IIIG valve train wear and oxidation test, which measures flat tappet cam and lifter wear as well as other parameters. This is not true of the new CK-4 specification.
Diesel engine oils have historically contained higher levels of the anti-wear additive ZDDP. With more oil marketers wishing to supply “universal” oils that meet both API SN requirements for gasoline engines and API CK-4 requirements for diesel engines, the levels of ZDDP have dropped in some CK-4 oils. Without the Sequence IIIG flat tappet cam wear test, it appears that some of these lower-ZDDP diesel oils are causing increased wear in diesel engines. This should serve as a word of caution for all users of diesel engine oil—regardless of whether you own a 6.7L Ford.