AMSOIL Synthetic Heavy Duty Diesel & Marine Motor Oil is a premium diesel oil that provides excellent performance in all types of diesel engines without exhaust aftertreatment systems, where highly effective control of wear and deposits is vital. Engineered with heavy-duty dispersant/detergent additives, its Total Base Number (TBN) of 12 neutralizes acids and controls soot thickening from exhaust gas recirculation (EGR) and blow-by to protect against corrosion, cylinder bore polishing (wear), varnish and sludge deposits. AMSOIL 15W-40 Diesel Oil resists heat and breakdown better than conventional petroleum oils for long-lasting performance and protection.

Extends Drain Intervals

AMSOIL Synthetic Heavy Duty Diesel & Marine Motor Oil can extend drain intervals far beyond those recommended for conventional petroleum oils. Its unique synthetic formulation and long-drain additive chemistry deliver maximum engine protection, cleanliness and performance over extended drain intervals, reducing vehicle maintenance and waste-oil disposal costs.

Controls Soot and Wear

AMSOIL Synthetic Heavy Duty Diesel  & Marine Motor Oil is heavily fortified with  detergent/dispersant additives and is naturally resistant to soot. It is designed to keep soot particles suspended independently and prevent them from aggregating to form larger, wear-causing particles. Viscosity increase is minimized and soot-related wear is reduced.

Reduces Oil Consumption and Emissions

AMSOIL Synthetic Heavy Duty Diesel & Marine Motor Oil has lower volatility than conventional petroleum oils. Oil consumption and emissions are minimized due to less vapor passing into the combustion chamber. Lower volatility helps AMSOIL 15W-40 Diesel Oil retain its viscosity after high-temperature service for continued dependable protection.

Excellent Cold-Flow Properties

AMSOIL Synthetic Heavy Duty Diesel & Marine Motor Oil eases cold-weather starting and provides vital startup lubrication to help prevent engine wear. It outperforms conventional 15W-40 petroleum oils and minimizes the impact of cold-weather operation.