API Service Classifications

CK-4 / FA-4

  • PC-11 is OFFICIAL. It is no longer a “proposed category”.
  • Engine designs are changing the demands on the oil.
  • As the oil companies lowered allowable levels of some additives (Sulfur, Phosphorous, and Sulfated Ash) in the oil to help lower emissions. However, this could be compromising engine durability.

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