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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
    Good for my baby duramax
    By  KEVIN,  a  Verified Buyer  from  Michigan   on  July 05, 2025
    I’ve been using this for about 100000 miles never had any issues. Even sent out sample for analysis. That confirmed it’s good to go.
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Trust
    By  Happy,  a  Verified Buyer  from  Indiana   on  July 04, 2025
    This is an oil I have trusted for nearly 20 years. Thanks for everything.
    Bottom Line
    Yes, I would recommend this to a friend.
    Was this review helpful?
  • 5 star rating
    Poor packing of oil filter
    By  DOUG,  a  Verified Buyer  from  Indiana   on  July 02, 2025
    My last 2 shipments the oil filter has been opened and exposed due to lack of better packing, top and bottom. This needs to be addressed
    Bottom Line
    Yes, I would recommend this to a friend.
    Was this review helpful?
  • 5 star rating
    Great diesel oil.
    By  WAYNE,  a  Verified Buyer  from  Pennsylvania  on  July 01, 2025
    I use this in my Kubota tractor in warm weather. Tractor has over 1000 hours with no problems.
    Bottom Line
    Yes, I would recommend this to a friend.
    Was this review helpful?
  • 5 star rating
    Awesome oil
    By  ART,  a  Verified Buyer  from  Texas  on  June 29, 2025
    Great oil, maintains it's viscosity through all my driving. Easy to order and love the containers it comes in.
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    25+Year User
    By  PERRY,  a  Verified Buyer  from  Sevierville, TN  on  June 29, 2025
    I have been using your oil and dual filters in my Tow Vehicles for over 25 years with great results. One 2500 GMC Duramax sold to a friend now has almost 300,000 miles mostly put on towing a travel trailer of some kind with no oil related problems at all.
    Was this review helpful?
  • 5 star rating
    Pleased with all the products purchased
    By  DALLAS,  a  Verified Buyer  from  Colorado  on  June 27, 2025
    Purchased this for my son. He always uses Amsoil products in his F-250 and is pleased with their performance.
    Bottom Line
    Yes, I would recommend this to a friend.
    Was this review helpful?
  • 5 star rating
    Good stuff
    By  PRESTON,  a  Verified Buyer  from  Alvarado TX   on  June 24, 2025
    Seems to be doing very well. There was an audible change in engine noise it sounded smoother and ran happier on my 2019 ram 3500
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 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.
    Was this review helpful?
  • 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?