Description Mobil Delvac 15W-40 are extra high performance diesel engine oils that help extend engine life in the most severe on and off-highway applications while delivering outstanding performance in modern, high-output, low-emission engines including those with Exhaust Gas Recirculation and Aftertreatment Systems with Diesel Particulate Filters and Diesel Oxidation Catalysts. Fully backwards compatible, Mobil Delvac will also deliver the same exceptional performance in older conventional engines. As a result, they meet or exceed the requirements of the API CJ-4, CI-4 PLUS and CH-4 service categories as well as key Original Equipment Manufacture requirements for 2007 engines.