Our Diesel Engine oil will improve fuel economy, extend drain intervals, minimize oil consumption and emissions, minimize engine friction and heat, as well as increasing the life of the engine by 2-4 fold. It also provides superior protection against corrosion, cylinder bore polishing, and varnish/sludge deposits. Alpha Megamoly Premium 15W-40 is our #1 selling product because it is simply the best petroleum diesel engine oil available on the market today. We use the most thermally stable additives available for diesel engine oil to ensure protection during the life of the oil. We also use an all Calcium Sulfonate additive in order to completely neutralize acid and eliminate soot.