
Signature Series Max-Duty Synthetic Diesel Oil 15W-40
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
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 15W-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

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
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

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.
Signature Series Max-Duty Synthetic Diesel Oil 15W-40
SDS
Download the SDS
Data Bulletins
Download the Data Bulletins
WARRANTY
Download the WARRANTY
Signature Series Max-Duty Synthetic Diesel Oil 15W-40
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Great diesel oilOverall great oilBottom LineYes, I would recommend this to a friend.
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best stuff in the marketbest stuff on the market use it in my truck and both my HarleysBottom LineYes, I would recommend this to a friend.
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Go to in Ford 6.7 powerstrokeWhen you ante up $10K for the industries most powerful diesel you want to take steps to ensure it is well kept. Have been using thee Signature Oil with the Amsoil by-pass system. Have been happy with the results. Highly recommended.Bottom LineYes, I would recommend this to a friend.
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Quiten that Diesel down!So, it was time to change the oil in my John Deere 2025r. Being a Amsoil PC I decided to try Amsoil in my tractor. I used Amsoil Engine Flush before pulling the plug and after draining my oil I'm glad I did! My oil was full of soot and carbon! After installing my Amsoil filter ( got the filter recommendation from Amsoil Tech.) I added some fresh Amsoil 5w-40 and started my JD up. I've never heard it run so quite! Almost sounded like a gas engine it was so quite! Looking forward to seeing if I can ' feel the protection' when I use it !! Thanks Amsoil!Bottom LineYes, I would recommend this to a friend.
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Best oil by farI used this oil for years in my truck and my cars. Best oil by any circumstancesBottom LineYes, I would recommend this to a friend.
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Diesel oilBy  ROBERT,  a  Verified Buyer  from  Brandon vermont  on  April 11, 2021I have been using this oil the truck has over 200 thousand miles and going strong I change it once a year and I also a change the filter at 6 months intervalsBottom LineYes, I would recommend this to a friend.
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Great oilLove this oil for my Duramax diesel. Just made a 3,000 mile trip and didn’t have to add any. Love the wide mouth of the quart container as it pours really fastBottom LineYes, I would recommend this to a friend.
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Diesel OilSuperior product.Bottom LineYes, I would recommend this to a friend.
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Awesome oil.I refuse to use any other oils in any of my vehicles. Truck bike boat tractor even lawnmower.Bottom LineYes, I would recommend this to a friend.
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Great oilI run this in my 7.3 powerstroke for 10k miles and change the oil filter halfway. So far no issues after 130kBottom LineYes, I would recommend this to a friend.