Signature Max-Duty 15W-40 Synthetic Diesel Oil

If you just want the best 15W-40 for your beloved diesel truck, you found it! This oil was built and intended for service by the owner which goes beyond the normal limitations of the engine or truck!

A best seller here in Sioux Falls!

Maximum-duty protection for your hardest-working diesel engines

Protect your investment in diesel power and confidently extend drain intervals with our top-grade synthetic diesel oil. AMSOIL Signature Series Max-Duty Synthetic Diesel Oil delivers 6X better wear protection than required by the Detroit Diesel DD13 Scuffing Test for Specification DFS 93K222. Advanced synthetic technology provides excellent viscosity control and outstanding extreme-temperature performance, while minimizing oil consumption. The result: protection that’s boosted to the max. Significantly less wear on cylinder liners equals more power and fuel economy.

Signature Series Max-Duty Synthetic Diesel Oil 15W-40This is the 15W-40 Offering Maximum Engine Protection

  • Delivers 6X more wear protection, delivering extra protection so you can push your diesel with peace of mind
  • Provides long-lasting wear protection, keeping cylinder liners looking like new
  • Delivers up to 60 percent better turbo cleanliness
  • Withstands the extra demands you place on the turbo when pulling heavy loads or updating the tune for maximum horsepower
  • Provides up to 2X better rust protection

Product Data Bulletin

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Also available in Stan Houston’s Sioux Falls Location on W 12th St.

15W-40 Viscosity Control

Using top-tier synthetic base oils, AMSOIL Signature Series Max-Duty is naturally resistant to oxidation and the thickening effects of soot contamination. That, along with boosted detergent/dispersant additives, keeps soot particles suspended independently, helping prevent the formation of larger, wear-causing particles. Viscosity increase is minimized and soot-related wear is controlled. Lower volatility also helps Signature Series Max-Duty retain its viscosity after high-temperature service for maximum engine protection and efficiency.

Excels in Extreme Temperatures

AMSOIL Signature Series Max-Duty Synthetic Diesel Oil resists thermal (heat) breakdown better than conventional and competing synthetic diesel oils. Unlike conventional oils, Signature Series contains no wax, staying fluid in sub-zero temperatures for easier starting, improved oil flow and reduced wear. Signature Series 0W-40 (DZF) has a broad viscosity range that offers 4X better cold-cranking ability than a 15W-40, making it excellent for use in both hot-operating engines and cold-weather starting extremes.

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Minimizes Oil Consumption

AMSOIL Signature Series Max-Duty has a low rate of volatility (burn-off), reducing oil consumption during operation and passing less oil vapor into the combustion chamber. It provides up to 76 percent less oil consumption than required by the API CK-4 standard in the Caterpillar-1N oil consumption test.


Provides up to 2X better rust protection for a diesel oil

Reduces Oil Consumption

Signature Series Max-Duty Synthetic Diesel Oil provides up to 76% less oil consumption.

reduced oil consumption by engine



Use in diesel engines and, where appropriate, gasoline engines requiring any of the following specifications:

  • API CK-4/SN, CJ-4, CI-4+, CF; CF-2
  • Volvo VDS4.5, VDS4, VDS3
  • Allison TES-439
  • Mack EOS-4.5, EO-O
  • Renault RLD-4, RLD-3
  • Cummins CES20086, CES20081
  • Caterpillar ECF-2, ECF-3, ECF-1-a
  • DDC 93K218, 93K215, 93K214
  • DFS 93K222
  • ACEA E9, E7
  • MB 228.31
  • MAN 3575
  • MTU Type 2.1, II, I
  • JASO DH-2
  • Deutz DQC III-10LA
  • Scania LA-2
  • Chrysler MS 10902
  • Ford WSS-M2C171-F1


Official oil badges


AMSOIL Signature Series Max-Duty Synthetic Diesel Oil is compatible with other conventional and synthetic engine oils. Mixing AMSOIL diesel oils with other oils, however, will shorten the oil’s life expectancy and reduce the performance benefits. AMSOIL does not support extended drain intervals where oils have been mixed.

Aftermarket oil additives are not recommended for use with AMSOIL synthetic diesel oils.


Diesel Engine Service Life
Heavy-Duty On-/Off-Road: Three times (3X) OEM1 recommendation, not to exceed 60,000 miles/600 hours or one year, whichever comes first.

Turbodiesel Pickup: Two times (2X) OEM1 recommendation, not to exceed 25,000 miles or one year, whichever comes first.

Competition Service Life: Provides lasting protection for multiple events. Use oil analysis to determine appropriate drain interval.

Gasoline Engine Service Life
Two times (2X) OEM1 recommendation, not to exceed 15,000 miles or one year, whichever comes first.

Drain intervals may be extended further with oil analysis.

1Refer to your owner’s manual for OEM drain interval recommendations and guidelines for severe and normal service.

Note: Extended drain intervals are not recommended for performance-modified engines, when using biofuels containing more than 10 percent ethanol or 15 percent biodiesel (B15) or for 2007-2009 Caterpillar* C13 and C15 on-highway engines. Extend drain intervals beyond OEM recommendations in these instances only with oil analysis. Note: 2007-2010 Dodge**, Ford** and GM** turbodiesel pickups are also not recommended for extended drain intervals when using DHD.

Buy in the Sioux Falls AMSOIL store at 47093 98th St just behind Marlins. or use this Online link to the Amsoil sale page if you are outside of the area.



AMSOIL products are backed by a Limited Liability Warranty. For complete information visit AMSOIL Warranty Information

* All trademarked names and images are the property of their respective owners and may be registered marks in some countries. No affiliation or endorsement claim, express or implied, is made by their use. All products advertised here are developed by AMSOIL for use in the applications shown.

Max Duty 15W-40 Reviews

Simply the best oil

By  MICHAEL,  a  Verified Buyer  from  Quebec Canada  on  October 12, 2023
This “magic” oil reduce by half the engine oil consumption of my truck!!

Diesel Oil 5W-40

By  RICK,  a  Verified Buyer  from  MA  on  September 06, 2023

Use Amsoil Signature Series Max-Duty Synthetic Diesel Oil 5W-40 for every oil change. Rated the best for Cummins diesels.


Using this oil for many years

By  MAHRAD,  a  Verified Buyer  from  Central Florida  on  August 27, 2023
I have been using the 15 W 40 Amsoil diesel oil for many years on different GMC Duramax diesels. All on lower mileage trucks. It is a good durable oil. No burning of loss of oil. No engine mechanical issues. I perform the oil changes myself. Libricity of the old oil is very good. The 2.5 gallon container is difficult to handle without spilling. I recommend getting it in quart size containers. I recommend the oil.

Great Diesel Oil

By  Curtis,  a  Verified Buyer  on  October 25, 2019
This oil is the finest quality I have ever run into. That is why it is in all our Diesel trucks.


Best oil for emission sensitive vehicles

By  Richard,  a  Verified Buyer  on  October 23, 2019

Use on my stock 2012 duramax with over 100,000 miles. No issues with dpf or other emission systems. With oil analysis, it holds up great for around 15,000 miles.


Looks like a good thing

By  Joseph,  a  Verified Buyer  on  October 22, 2019

Time will tell. Engine temperature down by 25 to 30 degrees


Definitely recommend Amsoil over any other brand

By  Michael,  a  Verified Buyer  on  October 11, 2019
I travel a lot fishing bass tournaments all over the country pulling a 21 foot bass boat and I immediately noticed a difference when I started using Amsoil in my Ram 2500 diesel. Engine runs quieter and smoother. Can’t say enough good things about Amsoil products.

Confused About Diesel Oil? We’ll help you

Your diesel truck is a serious investment – don’t skimp on protection. AMSOIL manufactures the best diesel oils on the market, providing the ultimate protection for your hard-working diesel engine, preserving the horsepower you crave and keeping you on the road.

We engineer our synthetic diesel oils with the same passion and pride you put into your turbodiesel, providing protection you can depend on in the most severe operating conditions.

Do you want extra engine protection?

Excessive wear to diesel cylinder liners and rings leads to increased oil consumption and loss of compression, reducing horsepower and fuel economy.

AMSOIL delivers rock-solid wear protection you can rely on.

Do you tow or haul?

Operating at up to 150,000 rpm in temperatures that exceed 1,000°F (538ºC), a turbocharger on a stock engine can dish out a lot of punishment to your oil.

If it’s not formulated to take the beating, the oil can break down, creating deposits and wear.

For some, stock engines don’t provide enough power, but dropping a tune on your engine puts even more stress on both your turbo and your oil.


Do you store your vehicles and equipment?

Intermittent use, prolonged storage, humidity and short drives can lead to the development of rust and corrosion, causing major damage to diesel engines.

Do you drive in hot temperatures?

AMSOIL synthetic diesel oils resist thermal (heat) breakdown better than conventional and competing synthetic diesel oils, effectively retaining their protective viscosities for added engine protection in extreme temperature conditions.

Do you drive in cold temperatures?

Unlike conventional oils, AMSOIL synthetic diesel oils contain no wax, staying fluid in sub-zero temperatures for easier starting, improved oil flow and reduced wear.

Signature Series 0W-40 has a broad viscosity range that offers 4X better cold-cranking ability than a 15W-40. Use the 0W-40 year round here in Sioux Falls  – no problem!

Find out how to keep diesel fuel from gelling in the cold.

Do you own a high-mileage vehicle?

AMSOIL synthetic diesel oils provide low rates of volatility (burn-off), reducing oil consumption during operation and passing less oil vapor into the combustion chamber.For example the Signature Series in 2017 and earlier Duramax engines per customer feedback yield a significant reduction in regens! The savings in fuel and agony is worth that alone.

Reduced oil consumption is especially important for the performance of your exhaust system.