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 5W-40 Heavy-Duty 100% Synthetic Diesel Oil.
AMSOIL 5W-40 Heavy-Duty 100% Synthetic Diesel Oil (ADO) is a fully synthetic API CK-4 diesel engine oil engineered for hard-working pickups, fleet trucks, and equipment that operate across wide temperature swings. Built on synthetic base oils with a balanced detergent and dispersant package, the 5W-40 grade meets API CK-4, CJ-4, CI-4+, CF, and CF-2, plus a broad list of Volvo, Mack, Renault, Cummins, Caterpillar, Detroit Diesel, ACEA, MB, MAN, MTU, JASO, Deutz, Chrysler, Ford, and Allison heavy-duty approvals. Heavy-Duty Synthetic Diesel Oil is the value-tier synthetic from AMSOIL: an upgrade over conventional, synthetic-blend, and competing synthetic diesel oils at OEM-recommended drain intervals.
Wear protection in heavy-duty service
Wear on rings and cylinder liners drives oil consumption up and pulls horsepower and fuel economy down. Heavy-Duty Synthetic Diesel Oil delivers 4X more wear protection than required by the Detroit Diesel DD13 Scuffing Test for specification DFS 93K222, based on third-party testing using 10W-30 as a worst-case representation. The 5W-40 grade records a 0.47 mm scar in the Four-Ball Wear Test (ASTM D4172) and holds a high-temperature high-shear viscosity of 4.2 cP (ASTM D5481), which supports a stable hydrodynamic film across hot bearings, ring belts, and turbo journals.
Cold-start flow for diesel pickups
The 5W-40 grade is the cold-weather workhorse for Power Stroke 6.7L, Cummins 6.7L, and Duramax pickups, especially in northern climates and unheated overnight storage. Heavy-Duty Synthetic Diesel Oil reaches a CCS viscosity of 5,581 cP at -30 C (ASTM D5293) and a pour point of -42 C (ASTM D97), so the formula flows dependably at sub-zero temperatures for faster oil-pressure pickup, less dry-start wear, and easier cranking. The viscosity index of 178 helps the same oil hold a 15.2 cSt working viscosity at 100 C (ASTM D445) once the engine is at temperature.
Soot control and viscosity stability
Synthetic base oils resist oxidation and the thickening effects of soot contamination. Detergent and dispersant additives keep soot particles suspended independently, helping prevent the formation of the larger, wear-causing particles that grind on liners, lifters, and rings. Lower volatility means less oil vapor passing into the combustion chamber, which helps the oil retain its working viscosity through high-temperature service for added engine protection and improved fuel economy. The 5W-40 grade carries a Total Base Number of 10.2 (ASTM D2896) to neutralize combustion acids over the full drain interval.
Reduced oil consumption
Heavy-Duty Synthetic Diesel Oil has a low rate of volatility (burn-off), reducing oil consumption during operation and passing less oil vapor into the combustion chamber. The formula provides up to 66 percent less oil consumption than required by the API CK-4 standard in the Caterpillar 1N oil consumption test. Lower oil consumption also means less topping off between services and less ash loading on diesel particulate filters and other emissions hardware.
Hot and cold temperature extremes
The 5W-40 grade is formulated to deliver improved heat and oxidation resistance compared to conventional diesel oils. It provides clean engine operation and helps maintain power and fuel efficiency for towing, hauling, idling, and long-haul service. The wide 5W-40 viscosity span covers winter starts in the north and sustained hot operation in the south without a seasonal oil swap.
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)
15.2
Kinematic Viscosity at 40 C, cSt (ASTM D445)
90.2
Viscosity Index (ASTM D2270)
178
CCS Viscosity, cP at -30 C (ASTM D5293)
5,581
Pour Point, C (ASTM D97)
-42
Four-Ball Wear Test scar, mm (ASTM D4172)
0.47
NOACK Volatility, percent weight loss (ASTM D5800)
Order AMSOIL 5W-40 Heavy-Duty 100% Synthetic Diesel Oil
AMSOIL 5W-40 Heavy-Duty 100% Synthetic Diesel Oil is available in quart bottle (ADOQT-EA), case of 12 quarts (ADOQT-CA), gallon jug (ADO1G-EA), 2.5 gallon jug (ADOTP-EA), 55 gallon drum (ADO55-EA), and 275 gallon tote (ADO27-EA). Using AMSOIL synthetic lubricants does not void a new vehicle or equipment manufacturer warranty, and all AMSOIL lubricants and filters are covered by the AMSOIL Limited Warranty. Confirm engine application match with the AMSOIL Vehicle Lookup Guide, compare grades and OEM approvals with the AMSOIL Diesel Oil Guide, then order AMSOIL 5W-40 Heavy-Duty 100% Synthetic Diesel Oil.
Is AMSOIL 5W-40 Heavy-Duty diesel oil the right grade for a Power Stroke, Cummins, or Duramax pickup?
5W-40 is one of the most-popular pickup diesel viscosities and is commonly used in Power Stroke, Cummins, and Duramax engines, especially where cold-start flow matters. Confirm the exact viscosity and current approvals through the live AMSOIL lookup and your owner's manual before changing oil.
How is Heavy-Duty different from Signature Series Max-Duty diesel oil?
Heavy-Duty Synthetic Diesel Oil is the value-tier synthetic diesel oil and is designed for the drain intervals stated by the original equipment manufacturer. Signature Series Max-Duty is the top-tier synthetic diesel oil and is engineered for extended drain capability beyond the OEM interval. Both lines are fully synthetic and meet API CK-4. Compare the two families in the AMSOIL Diesel Oil Guide.
What drain interval does Heavy-Duty 5W-40 support?
Heavy-Duty Synthetic Diesel Oil is recommended for the drain intervals stated by the original equipment manufacturer. Refer to the owner's manual for the specific oil change interval. Intervals may be extended beyond the OEM-recommended interval only with oil analysis. For competition or racing service, oil analysis determines the appropriate drain interval.
How do I confirm current approvals?
Confirm the current API category, OEM approvals, and viscosity guidance on the live AMSOIL product page before service. Approval lists can change when formulas or manufacturer requirements are updated.
Can Heavy-Duty 5W-40 be mixed with conventional or other synthetic diesel oils?
The formula is compatible with other conventional and synthetic oils, but mixing AMSOIL diesel oil with other oils will reduce its performance benefits. Aftermarket oil additives are not recommended for use with AMSOIL synthetic diesel oils.
Will running AMSOIL synthetic diesel oil void a new engine warranty?
No. Using AMSOIL synthetic lubricants does not void a new vehicle or equipment manufacturer warranty, and all AMSOIL lubricants and filters are covered by the AMSOIL Limited Warranty.
