Signal Tech Heavy Duty Diesel Engine Oils is a line of premium performance multigrade diesel engine oils that deliver an industry leading protection against increased wear which can lead to lower productivity and impaired fuel economy. They’re formulated to exceed API CK-4, CJ-4, CI-4, CI-4 Plus and older. The product is particularly suitable for use in emission compliant engines that utilize heavy EGR and exhaust after-treatment devices such as Diesel Particulate Filters (DPFs_ with or without Diesel Oxidation Catalysts (DOCs) and Selective Catalytic Reduction (SCR). Signal Tech Heavy Duty Diesel Engine Oils provide advanced performance in low-emission certified diesel engines that are equipped with EGR, older non-EGR containing diesel engines, and off-highway diesel engines.