By now, you’re probably already using PC-11 or are about to. To date, ExxonMobil has accumulated more than 27-million miles of testing on its CK-4 and FA-4 PC11 diesel engine oil blends. The main thing fleet owners need to remember is there are two sub-categories, CK-4 and FA-4:
• CK-4 – replaces CJ-4 oils, is a higher-viscosity blend with the high-temp, high-shear qualities needed for older-style diesel engines and is back-serviceable.
• FA-4 – In order to meet increasing emissions and fuel efficiency standards, new diesel engine designs will benefit from using a lower viscosity engine oil. FA-4 does not have the same high-temp, high-shear qualities as CK-4 and is not back-serviceable.