Hi-Tec Fleetmaster CK-4 Extreme 15W/40 is an API CK-4 heavy-duty diesel engine oil formulated using the latest synthetic technology base oils for use in severe-duty high-speed four-stroke diesel engines with DPF, cooled EGR and other exhaust treatment systems, both turbocharged and normally aspirated. It is designed to offer greater durability and protection due to its increased shear stability and reduced oxidative thickening, abrasive wear bore polishing and piston deposits. Hi-Tec Fleetmaster CK-4 Extreme 15W/40 can be used in 2017 model vehicles as well as those requiring Euro VI emission standards and can replace CJ-4 engine oils. It is backward compatible with most applications where engine manufacturers currently recommend CJ-4, CI-4 Plus, CI-4, and CH-4 performance specifications.