Mobilgard HSD 15W-40 by Mobil is an extra high performance, multi-grade engine oil specifically formulated for severe service high-speed diesel engines in marine applications. Its advanced chemistry provides outstanding performance in both modern, demanding low-emission diesel engines and older diesel engines operating on low or high sulphur distillate fuel. Mobilgard HSD 15W-40 is approved or recommended by all the major marine high-speed diesel engine builders.