Skip to Main Content
Close Icon

Main Menu

Begin typing to search, use arrow keys to navigate, Enter to select.
Your order may take longer than normal to arrive, and some products may be unavailable. We are working hard to overcome supply-chain issues and freight-carrier delays. Learn more.
Roll over image to zoom in

Signature Series Max-Duty Synthetic Diesel Oil 5W-40

Product code : DEOQT-EA

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

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

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

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

Signature Series Max-Duty Synthetic Diesel Oil 5W-40



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.

Signature Series Max-Duty Synthetic Diesel Oil 5W-40



Signature Series Max-Duty Synthetic Diesel Oil 5W-40

  • 5 star rating
    Good oil.
    By  GARY,  a  Verified Buyer  from  Ft Worth Tx.   on  July 06, 2022
    Just changed oil in our new Chevy Duramax 3500HD 3000 miles on truck. pulled 33 ft toy hauler to Colorado 1800 miles round trip an used 1/4 quart of oil. Will continue using Amsoil in all my engines.
    Bottom Line
    Yes, I would recommend this to a friend.
    Was this review helpful?
  • 5 star rating
    confident
    By  WILLIAM,  a  Verified Buyer  on  July 04, 2022
    i have used amsoil back from the 70's, i use all of these in all my stuff
    Bottom Line
    Yes, I would recommend this to a friend.
    Was this review helpful?
  • 5 star rating
    Diesel oil
    By  GARY,  a  Verified Buyer  from  Arizona   on  July 03, 2022
    Awesome oil been running this oil in my 2018 Ram 2500 since second oil change and currently at 97,000 miles.
    Bottom Line
    Yes, I would recommend this to a friend.
    Was this review helpful?
  • 5 star rating
    customer for live
    By  BOB,  a  Verified Buyer  from  ontario canada  on  July 01, 2022
    I`m 70 years old was in the auto repair business for 49 years. involved in racing my whole life an currently drag race a challenger hellcat. I decided to forge the bottom end of the motor an could not believe how good everything looked inside the motor. connecting rod bearings look like they just came out of the box. pistons an cylinder walls are perfect. but at the same time not all that surprised . always used amsoil an will continue to do so.
    Bottom Line
    Yes, I would recommend this to a friend.
    Was this review helpful?
  • 5 star rating
    Great oil
    By  GREG,  a  Verified Buyer  on  July 01, 2022
    The engine runs cooler and smoother with this oil. Plus I get 7500 to 9000 miles between changes.
    Bottom Line
    Yes, I would recommend this to a friend.
    Was this review helpful?
  • 5 star rating
    Great oil
    By  MICHAEL,  a  Verified Buyer  from  Wilmington  on  June 30, 2022
    Best on the market.
    Bottom Line
    Yes, I would recommend this to a friend.
    Was this review helpful?
  • 5 star rating
    Saves time
    By  TUCKER,  a  Verified Buyer  from  Maine  on  June 23, 2022
    I run this in all of my diesel equipment (tractor, excavator, ram 5500, generator) and only change once a year regardless of miles/hours. This saves me time and money from having to do multiple changes if running conventional oil. It also seems to have a much higher retention/suspension capacity for contaminants than other oils.
    Bottom Line
    Yes, I would recommend this to a friend.
    Was this review helpful?
  • 5 star rating
    40 year user
    By  ROD,  a  Verified Buyer  on  June 21, 2022
    Been using for 40 yrs. Best of the Best.
    Bottom Line
    Yes, I would recommend this to a friend.
    Was this review helpful?
  • 5 star rating
    Purebred Synthetic.
    By  SCOTT,  a  Verified Buyer  from  SE USA  on  June 20, 2022
    I am so impressed with the results of the laboratory oil analysis since switching to AMSOIL Signature Synthetic motor oils. AMSOIL is a company with a spine of integrity.
    Bottom Line
    Yes, I would recommend this to a friend.
    Was this review helpful?
  • 5 star rating
    Trust your oil...
    By  William,  a  Verified Buyer  from  California  on  June 18, 2022
    I will always use products I can trust in. Amsoil is at the head of my list! I have created quite a few converts. Autos and trucks are usually the second biggest investment in a person's life so DO NOT trust any old oil. I'll stick to this brand so I won't have something else to worry about.
    Bottom Line
    Yes, I would recommend this to a friend.
    Was this review helpful?