AMSOIL 15W-40 HEAVY-DUTY 100% SYNTHETIC DIESEL OIL

AMSOIL 15W-40 Heavy-Duty 100% Synthetic Diesel Oil delivers serious wear protection and viscosity stability for diesel trucks, heavy equipment, and fleet vehicles that run hard in demanding conditions. It is a direct upgrade over conventional and synthetic-blend 15W-40 diesel oils, built with synthetic base oils that outperform where it counts.

Diesel engines face punishing conditions. High combustion temperatures, heavy loads, soot contamination, and extended operation all conspire to break down oil faster than most formulations can handle. Ring and liner wear leads to compression loss, increased oil consumption, and reduced horsepower. The oil you run has to resist all of that without losing its protective properties between drain intervals.

4X MORE WEAR PROTECTION
Wear on rings and cylinder liners is the single biggest threat to long-term diesel engine health. Once wear begins, oil consumption climbs, compression drops, and fuel economy suffers. Third-party testing in the Detroit Diesel DD13 Scuffing Test for specification DFS 93K222 shows AMSOIL Heavy-Duty Synthetic Diesel Oil delivers 4X more wear protection than the standard requires. That level of protection directly translates to longer equipment life and fewer unplanned service events. For Cummins ISX, Caterpillar C15, Detroit DD15, and other hard-working diesel engines, this is a measurable advantage over conventional 15W-40 oils.

MINIMIZES OIL CONSUMPTION
Oil consumption is more than just an inconvenience. It means oil vapor entering the combustion chamber, accelerated DPF loading, and the constant need to top off between changes. AMSOIL Heavy-Duty 15W-40 Synthetic Diesel Oil provides up to 66 percent less oil consumption than required by the API CK-4 standard in the Caterpillar-1N oil consumption test. The NOACK volatility of the 15W-40 is just 3.6 percent weight loss, which is exceptionally low for this viscosity grade. Less burn-off means you keep more oil in the sump and less ash in the aftertreatment system.

VISCOSITY CONTROL UNDER SOOT LOADING
Soot is unavoidable in diesel combustion. The problem is what happens when soot particles agglomerate into larger clusters. Those clusters thicken the oil, increase viscosity beyond its intended grade, and act as abrasives on bearing surfaces. AMSOIL Heavy-Duty Synthetic Diesel Oil uses advanced detergent and dispersant additives to keep soot particles suspended independently, preventing the formation of larger, wear-causing agglomerates. The oil resists oxidation-driven thickening and retains its viscosity after prolonged high-temperature service, helping maintain both engine protection and fuel economy across the full drain interval.

PERFORMS IN EXTREME TEMPERATURES
Cold-weather startups put enormous stress on diesel engines. Oil that doesn't flow quickly leaves bearings, cam lobes, and cylinder walls unprotected during the most critical moments of operation. AMSOIL 15W-40 Heavy-Duty Synthetic Diesel Oil has a CCS viscosity of 4,932 cP at -20°C and a pour point of -38°C (-36°F), so it flows reliably in cold temperatures for faster oil pressure buildup and reduced dry-start wear. On the hot side, a High-Temperature/High-Shear viscosity of 4.7 cP confirms that the oil maintains a robust protective film under high loads and elevated temperatures. Trucks running Caterpillar, Cummins, or Detroit engines in everything from northern winter cold starts to summer hauling in the desert get consistent protection across the full temperature range.

SPECIFICATIONS AND COMPATIBILITY
AMSOIL 15W-40 Heavy-Duty Synthetic Diesel Oil meets a broad range of OEM and industry specifications, making it suitable for mixed fleets and a wide variety of diesel-powered equipment. Specifications include API CK-4, CJ-4, CI-4 Plus, and CF. It also meets Cummins CES 20086 and CES 20081, Caterpillar ECF-2, ECF-3, and ECF-1-a, Detroit Diesel DFS 93K222, DFS 93K218, DFS 93K215, and DFS 93K214, Volvo VDS-4.5, VDS-4, and VDS-3, Mack EOS-4.5 and EO-O, Chrysler MS 10902, Ford WSS-M2C171-F1, JASO DH-2, JASO MA and MA2, MAN 3575, MTU Type 2.1, Type II, and Type I, Deutz DQC III-10LA, Allison TES439, MB 228.31, ACEA E9 and E7, and Renault RLD-4 and RLD-3. All viscosities in the Heavy-Duty line are also capable of gasoline service per API SN. The oil is compatible with conventional and synthetic oils, though mixing will reduce performance benefits. Aftermarket oil additives are not recommended.

SERVICE LIFE
AMSOIL Heavy-Duty 15W-40 Synthetic Diesel Oil is recommended for the drain intervals stated by the original equipment manufacturer. Intervals may be extended beyond the OEM recommendation with oil analysis. For competition or off-highway applications, oil analysis should be used to determine the appropriate drain interval.