SFR Ultimate Series Diesel Engine Motor Oils are formulated for extended drain service in the most demanding applications. We start with an API Service Category CK-4 Plus, which meets the new EGR (Exhaust Gas Re-circulation) and ACERT (Advanced Combustion Emission Reduction Technology); We then add SFR's premium oil fortifier package to provide the ultimate motor oil in extending drain intervals, reducing wear up to 28% over the leading brand, and improving fuel economy. Our Ultimate Series Diesel Motor Oils provide higher oil film thickness, improved oxidation control at higher temperatures, improved soot handling and shear stability performance in all diesel engines.