Developed to provide protection beyond conventional, synthetic-blend, and other synthetic oils. AMSOIL synthetic technology delivers heavy-duty protection for diesel enthusiasts and those who depend on their trucks and equipment to make a living.
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Product data sheets
View, download, or save a copy of the Product Data Sheet or Safety Data Sheet for AMSOIL 15W-40 Heavy-Duty 100% Synthetic Diesel Oil.
AMSOIL 15W-40 Heavy-Duty 100% Synthetic Diesel Oil (ADP) is the workhorse SAE 15W-40 grade in the AMSOIL diesel lineup, formulated for over-the-road tractors, work pickups, agricultural and construction equipment, and on-and-off-road fleets that follow OEM-recommended drain intervals. The synthetic base oils and detergent/dispersant additive system handle soot loading, high cylinder pressures, and the temperature range a diesel sees between cold mornings and full-load summer hauls.
Heavy-duty wear protection on rings and cylinder liners
Ring and liner wear is the failure mode that ends a diesel engine. Worn rings let combustion gases blow past into the crankcase and pass oil into the combustion chamber, robbing compression, horsepower, and fuel economy. AMSOIL 15W-40 Heavy-Duty 100% Synthetic Diesel Oil delivers 4X more wear protection than required by DFS 93K222, based on third-party testing in the Detroit Diesel DD13 Scuffing Test with a 10W-30 as worst-case representation. The 0.46 mm Four-Ball Wear Test scar (ASTM D4172) and 4.7 cP High-Temperature/High-Shear viscosity (ASTM D5481) translate that bench result into a durable film at the ring belt and bearings.
Soot handling and viscosity control
Diesel soot is the biggest reason a heavy-duty oil thickens in service. The advanced detergent/dispersant additive package keeps soot particles suspended independently so they do not agglomerate into the larger, wear-causing aggregates that abrade rings, liners, and valve train. Total Base Number of 10.2 (ASTM D2896) gives the formulation reserve alkalinity to neutralize combustion acids in high-EGR engines through a full OEM drain. Viscosity index of 144 (ASTM D2270) keeps the SAE 40 film strength at operating temperature instead of shearing toward a 30-weight under soot loading and oxidation.
Low oil consumption and low volatility
Low NOACK volatility means less light hydrocarbon vapor passing through the PCV system into the intake, into the EGR cooler, and onto turbocharger turbine vanes. NOACK volatility of 3.6 percent weight loss (ASTM D5800) for the 15W-40 grade is well below the API CK-4 limit and helps keep aftertreatment hardware cleaner over time. The same low-volatility chemistry produces up to 66 percent less oil consumption than required by the API CK-4 standard in the Caterpillar-1N oil consumption test, reducing the volume of top-off oil between drains for fleets that track cost per mile.
High-temperature oxidation resistance
Heat-stable synthetic base oils resist oxidation and the deposit formation that follows. The formulation maintains its in-grade viscosity after high-temperature service, supporting bearing oil films during peak EGT events such as grade pulls, regenerations, and PTO work. Sulfated ash content of 1.0 percent by weight keeps the formulation within heavy-duty low-SAPS targets so DPF, SCR, and EGR hardware reach designed service life.
Cold-temperature flow and pumpability
A 15W-40 still has to flow on a cold morning. The Cold Crank Simulator viscosity of 4,932 cP at -20 degrees Celsius (ASTM D5293) and pour point of -38 degrees Celsius (-36 degrees Fahrenheit, ASTM D97) give the formulation margin below the operability floor of a typical 15W-40 for fleets running in northern states and Canadian winters.
Recommended applications and service guidance
Use the live AMSOIL product page and your owner's manual to confirm the current viscosity, API category, OEM approvals, and service guidance for your engine before ordering. AMSOIL updates approvals and recommendations as formulas and manufacturer requirements change.
For extended service, follow the current AMSOIL guidance, your equipment manual, and oil-analysis results. Extended intervals are not appropriate for every engine or operating condition, especially modified engines, unusual fuels, racing use, or equipment with special service restrictions.
Typical technical properties
Property
Value
Kinematic Viscosity at 100°C, cSt (ASTM D445)
15.5
Kinematic Viscosity at 40°C, cSt (ASTM D445)
112.7
Viscosity Index (ASTM D2270)
144
Cold Crank Simulator Viscosity at -20°C, cP (ASTM D5293)
4,932
Pour Point, °C (°F) (ASTM D97)
-38 (-36)
Four-Ball Wear Test, scar diameter, mm (ASTM D4172)
0.46
NOACK Volatility, percent weight loss (ASTM D5800)
Order AMSOIL 15W-40 Heavy-Duty 100% Synthetic Diesel Oil
Available package codes are ADPQT-EA (quart), ADPQT-CA (case of 12 quarts), ADP1G-EA (gallon jug), ADPTP-EA (2.5 gallon jug), ADP55-EA (55 gallon drum), and ADP27-EA (275 gallon tote). All AMSOIL synthetic lubricants are backed by the AMSOIL Limited Warranty against defects in materials and workmanship. Cross-check engine fit with the AMSOIL vehicle lookup guide, and compare Heavy-Duty against Signature Series Max-Duty in the AMSOIL diesel oil guide. Order Now.
How does Heavy-Duty 15W-40 compare with Signature Series Max-Duty 15W-40?
Both are 100 percent synthetic and share heavy-duty OEM coverage. AMSOIL 15W-40 Heavy-Duty 100% Synthetic Diesel Oil is the value tier built around OEM-recommended drain intervals. Signature Series Max-Duty 15W-40 is the extended-drain tier, formulated for longer service intervals under severe service and validated for higher soot capacity. Fleets that change oil on OEM or oil life monitor schedules sit in the Heavy-Duty tier; owner-operators and severe-service users that target maximum drain intervals choose Max-Duty.
What engines and trucks use AMSOIL 15W-40 Heavy-Duty Synthetic Diesel Oil?
The 15W-40 viscosity covers Cummins B and ISX families, Detroit DD-series, Caterpillar C-series, Volvo D-engines, Mack MP-series, and Duramax and Power Stroke engines where the owner manual lists a 15W-40 option. Class 6 to Class 8 over-the-road trucks, work pickups, agricultural tractors, construction equipment, generators, and stationary diesels using API CK-4 or back-serviceable CJ-4 are common applications.
Will running this oil void a new-truck warranty?
No. Using AMSOIL synthetic lubricants does not void the new-vehicle warranty. The Magnuson-Moss Warranty Act protects the consumer right to use a qualified aftermarket lubricant that meets the OEM specification. AMSOIL 15W-40 Heavy-Duty 100% Synthetic Diesel Oil meets the API, ACEA, and OEM specifications listed in the Recommended applications section above. AMSOIL synthetic lubricants are also backed by the AMSOIL Limited Warranty against defects in materials and workmanship.
Is it compatible with DPF, DEF, and SCR aftertreatment systems?
Yes. The formulation meets API CK-4 and CJ-4 low-SAPS targets at 1.0 percent sulfated ash, which is the chemistry envelope diesel particulate filters, diesel exhaust fluid systems, and selective catalytic reduction catalysts were designed around. Low NOACK volatility of 3.6 percent further reduces the volume of oil vapor reaching the intake, EGR cooler, and turbocharger over the life of the oil.
Can it be mixed with conventional or other synthetic diesel oils?
The formulation is compatible with other conventional and synthetic diesel oils, so a top-off in an emergency will not damage the engine. Mixing oils with different additive and base-stock chemistries dilutes the synthetic performance benefits, so a full drain and refill with the same product is the right plan for normal service. Aftermarket oil additives are not recommended for use with AMSOIL synthetic diesel oils.
How long can a fleet run between drains?
AMSOIL 15W-40 Heavy-Duty 100% Synthetic Diesel Oil is recommended for the drain intervals stated by the original equipment manufacturer. Refer to the owner manual or the oil life monitor for the specific service interval. Intervals may be extended beyond the OEM-recommended drain with used oil analysis from a qualified lab. The formulation also provides lasting protection for multiple events during competition use, again with oil analysis setting the drain.
