VALVE AS-FLUID SAMPLING 3937271 - Caterpillar

The References have been revised to include the latest recommendations.
The latest oil recommendation for Caterpillar engines is the new American Petroleum Institute (API) performance category CF-4 (except for 3600 Engines). Oils in this category were originally developed to meet emission regulations for the United States truck engine market. They are now recommended for Caterpillar engines used in other applications because of operation with higher piston temperatures. Both the regulated emissions engines and the engines used in machine, industrial, generator set, and marine applications are operating at higher temperatures. The newer designed engines with the two-piece ferrous/aluminum pistonsand even engines with the one piece aluminum pistons are operating at temperatures higher than in the past.
The "older" oils are failing because they allow heavier piston crownland deposits. This can lead to the top ring not seating correctly which can result in loss of oil control. When the top ring does not function correctly, both combustion gas blowby and oil consumption increase. This can result in further deterioration. As piston crownland deposits build, the clearance between the piston and liner decrease until the carbon deposits begin to rub on the liner. The rubbing of the carbon deposits will polish the liner (wear off the honing pattern). As the liner becomes polished, the oil is not retained on the liner to provide lubrication to the rings and piston skirt. This can result in scuffing and seizure of the these components with serious engine damage.