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AMSOIL Signature Series 15W-40 100% Synthetic Max-Duty Diesel Oil

Product code : DMEQT-EA

  • Outstanding extreme-pressure protection
  • Delivers 6X more wear protection1
  • Maintains proper viscosity (thickness) 
  • Minimizes oil consumption
  • Maximizes fuel efficiency
  • Excels in extreme temperatures 
  • Confidently extend drain intervals

     

    1Based on third-party testing in the Detroit Diesel DD13 Scuffing Test for specification DFS 93K222 using 5W-30 as worst-case representation

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AMSOIL Signature Series 15W-40 100% Synthetic Max-Duty Diesel Oil



Developed to protect the horsepower diesel enthusiasts crave and extend the life of hard-working commercial equipment in the most severe conditions. Signature Series synthetic technology delivers max-duty protection in on- and off-road applications.

See the Product Data Bulletin for full details.

MAXIMUM ENGINE PROTECTION

  • Delivers 6X more wear protection,1 delivering extra protection so you can push your diesel with peace of mind
  • Provides long-lasting wear protection, keeping cylinder liners looking like new2
  • Delivers up to 60 percent better turbo cleanliness3
  • 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 protection4

1Based on third-party testing in the Detroit Diesel DD13 Scuffing Test for specification DFS 93K222 using 5W-30 as worst-case representation
2Based on independent testing of AMSOIL 5W-30 Signature Series Max-Duty Synthetic Diesel Oil and a leading conventional 15W-40 diesel oil using the Detroit Diesel* DD13 Scuffing test for specification DFS 93K222.
3Based on specification standards of CAT C13 2nd Ring Top Land Carbon testing
4Based on industry standard testing using the NMMA FC-W Rust Test.


Delivers More Wear Protection

Third-party testing shows Signature Series Max-Duty Synthetic Diesel Oil delivers 6X more protection against wear than required by Detroit Diesel’s* standard.II

IIBased on third-party testing in the Detroit Diesel DD13 Scuffing Test for specification DFS 93K222 using 5W-30 as worst-case representation.
*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.


AMSOIL Fights Wear

AMSOIL delivers powerful engine protection. How good is it? In third-party testing compared to a leading brand, AMSOIL provided long-lasting wear protection, keeping cylinder liners looking like new.DD

AMSOIL Fights Wear – AMSOIL delivers powerful engine protection. How good is it? In third-party testing compared to a leading brand, AMSOIL provided long-lasting wear protection, keeping cylinder liners looking like new.

DDBased on third-party testing of AMSOIL 5W-30 Signature Series Max-Duty Synthetic Diesel Oil and a leading conventional 15W-40 diesel oil using the Detroit Diesel* DD13 Scuffing test for specification DFS 93K222.
*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.


Keeps Turbos Clean

AMSOIL Signature Series Max-Duty Synthetic Diesel Oil provides protection boosted to the max, delivering up to 60% better turbo cleanlinessJ and withstanding the extra demands you place on the turbo when pulling heavy loads or updating the tune for maximum horsepower.

JBased on specification standards of CAT C13 2nd Ring Top Land Carbon testing


Protects Against Rust

Provides up to 2X better rust protection.K Protects Against Rust – Provides up to 2X better rust protection.

KBased on industry standard testing using the NMMA FC-W Rust Test.


VISCOSITY CONTROL

  • Resists oxidation and the thickening effects of soot contamination
  • Retains viscosity after high-temperature service for maximum engine protection and efficiency
  • Provides up to 76 percent less oil consumption5

5Than required by the API CK-4 standard in the Caterpillar-1N oil consumption test


Reduces Oil Consumption

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

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

LThan required by the API CK-4 standard in the Caterpillar-1N oil consumption test.


EXCELS IN EXTREME TEMPERATURES

  • Provides outstanding protection and performance in hot and cold temperature extremes
  • Resists thermal (heat) breakdown better than conventional and competing synthetic diesel oils.
  • Stays fluid in sub-zero temperatures for easier starting, improved oil flow and reduced wear.

See the Product Data Bulletin for full details.

AMSOIL Signature Series 15W-40 100% Synthetic Max-Duty Diesel Oil

Data Bulletin

Warranty

SDS



AMSOIL Signature Series 15W-40 100% Synthetic Max-Duty Diesel Oil

  • 5 star rating
    long time user no complaints
    By  MAHRAD,  a  Verified Buyer  from  central florida  on  June 20, 2025
    have been using the 15W 40 Amsoil diesel oil since my 2020 GMC 3500 was new. No oil consumption, changing the engine oil every 10,000 miles.
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Great product
    By  JEFF,  a  Verified Buyer  on  June 18, 2025
    Comes quick and great oil.
    Bottom Line
    Yes, I would recommend this to a friend.
    Was this review helpful?
  • 5 star rating
    Great oil
    By  PHILIP,  a  Verified Buyer  on  June 11, 2025
    I only use the AMSOIL diesel oil in my truck. At 300,000 miles, I replaced the injectors and when the valve cover was removed, the all of the metal components looked as clean as if the engine was brand new.
    Bottom Line
    Yes, I would recommend this to a friend.
    Was this review helpful?
  • 5 star rating
    Great product
    By  MARK,  a  Verified Buyer  from  Lake Havasu City, AZ  on  June 09, 2025
    Great product for a great price.
    Bottom Line
    Yes, I would recommend this to a friend.
    Was this review helpful?
  • 5 star rating
    First Amsoil purchase
    By  KEITH,  a  Verified Buyer  from  Florida  on  June 04, 2025
    I own a 2020 Ram 2500 6.7L Cummins diesel, and I was tired off the dealership. I switched because of Amsoil brand name, and the unbelievable amount of positive reviews. The ordering and shipping were easy and very quick. The product and shipping box were not damaged, hint at another retail shipping giant. I cannot comment on how the oil is working, as it has not even been 500 miles since my oil change. I will buy again and have!
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Great motor oil
    By  WADE,  a  Verified Buyer  from  Houston  on  June 03, 2025
    I use this oil for my F350. Life of the oil is great. Keeps my motor running smoothly. Can't ask for better.
    Bottom Line
    Yes, I would recommend this to a friend.
    Was this review helpful?
  • 5 star rating
    2017 Super Duty
    By  JR,  a  Verified Buyer  from  Elwood, Indiana  on  June 02, 2025
    The only oil and filter I use in any of my vehicles is Amsoil! This truck gained about 1 MPG after the 1st oil change with Amsoil! To me Amsoil means less maintenance more miles and hassle free service! I order on-line and have it within 3 days!
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    50 hour service for Kioti CK2620 hst
    By  SCOT,  a  Verified Buyer  from  Northern California   on  May 30, 2025
    I used this oil for a Kioti CK2620 hst compact diesel tractor. After changing out the oil the engine definitely ran quieter. My decision to use this oil was based on reading countless entries on light equipment forums and also reviews of many Amsoil users.
    Bottom Line
    Yes, I would recommend this to a friend.
    Was this review helpful?
  • 5 star rating
    Great product
    By  FRED,  a  Verified Buyer  from  Holyoke, CO  on  May 30, 2025
    I believe in superior lubrication protection for my 6.7 Cummins.
    Bottom Line
    Yes, I would recommend this to a friend.
    Was this review helpful?
  • 5 star rating
    10 years
    By  DAVID,  a  Verified Buyer  from  Reno, Nevada  on  May 29, 2025
    oil test show wear on engine is almost none. Much better than what I used before. Also, the gear lube for my Polaris general has my front and rear differential quiet and clean. Overall I use AMSOIL in every motor on the property.
    Bottom Line
    Yes, I would recommend this to a friend.
    Was this review helpful?