API CK-4 and API FA-4 engine oils will see major upgrades in performance. These oils offer improved fuel efficiency, oxidation performance, shear stability protection and resistance to aeration.

To classify the oils, a rigorous testing process must be undertaken. Figure 1 shows the various tests that have been carried out on lubricants in the past. The current generation does everything the previous generation did, and more.

“Almost all of the tests are carried over from CJ-4. What we’ve added are some more severe tests, such as the Mack T13, which will measure oxidation under higher temperature conditions, better simulating the higher temperatures seen in modern engines," notes Keith Corkwell, Lubrizol's heavy-duty diesel Global Business Manager. “Shear stability has seen a change in blending requirements, to ensure oils are less likely to thin out of grade. The CAT Aeration Test replaces the older Engine Oil Aeration Test (EOAT), which was based on hardware that isn’t available anymore.”