Synthetic Heavy-Duty Diesel & Marine Motor Oil SAE 15W-40 (AME) Engineered for all types of diesel engines with an emphasis on modern, low emission heavy duty diesel engines. High 12 TBN controls acids from combustion blow-by and EGR. High levels of detergency and dispersancy additives control soot thickening, oxidation and wear. Resists bore polishing, deposit formation and ring sticking. Provides clean engine performance.