Gulf Supreme Duty LE (CI4-Plus) 15W40 (210L) is an extra high performance heavy duty diesel engine oil specifically developed to extend engine life in the most severe duty on and off-highway applications. The advanced formulation technology of this product ensures exceptional performance in modern, high output, low emission engines including those employing Exhaust Gas Recirculation (EGR) systems, as well as older engines operating on diesel fuel with low or high sulphur. It meets the latest performance requirements of major American and European OEMs