OTR 15W-40 Synthetic Blend Motor Oil ensures Expertise Built In™, being a new generation of diesel engine protection engineered to react to the unique demands of diesel engine security in applications that need API CK-4. This heavy duty synthetic blend has unique additives and technology that promise superior oxidation and thermal balance while guarding against the destructive effects of cold temperature start-ups. FleetPride is your First Click in Heavy Duty®.