Gulf Supreme Duty ULE (CK4) 10W30 (210L) is premium performance heavy duty diesel engine oil specially developed for use in ultra low emission engines meeting the latest US and European emission standards. This oil addresses the unique needs of the latest engines and enhances the life of exhaust after treatment devices. It is formulated with state-of-the-art additive technology and severely hydroprocessed base oils to provide excellent performance and overall protection having a potential to offer extended drain intervals. It meets the performance requirements of API CK-4 service category. It is also backward compatible for the use in older engines requiring API CJ-4 and below quality oils.