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AMSOIL Signature Series 5W-40 100% Synthetic Max-Duty Diesel Oil

Product code : DEOQT-EA

4.9 star rating Read 1,571 reviews

Customer Rating

4.9

92% would recommend

  • 5 1505
  • 4 45
  • 3 10
  • 2 3
  • 1 8

AMSOIL Signature Series 5W-40 100% Synthetic Max-Duty Diesel Oil

4.9 star rating Based on 1,571 reviews
  • 5 star rating
    Mechanic impressed
    By  MOISES,  a  Verified Buyer  from  TX  on  January 12, 2026
    My local dealership recently had to replace the upper oil pan gasket. When I went to pick up my vehicle, the mechanic asked what type of oil I used. He was extremely impressed by the internal cleanliness of my engine at 120,000 miles.
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Oil change
    By  DELBERT,  a  Verified Buyer  from  Kentucky   on  January 11, 2026
    I am happy with the diesel max oil I have been using it in my dually for a couple years and decided to switch my 2021 jeep gladiator diesel to it also both of them run great I will stay with it because it works well.i will be switching my farm tractor over to amsoil.
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Best motor oil period!!
    By  DANE,  a  Verified Buyer  on  January 11, 2026
    Been using amsoil for years!! Hands down the best there is!
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Duramax
    By  ROJELIO,  a  Verified Buyer  from  San Diego   on  January 11, 2026
    👍🏼
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Diesel Oil Review
    By  ROD,  a  Verified Buyer  from  Fort Myers, FL  on  January 10, 2026
    Only oil I have ever used in my 2016 EcoDiesel. Running strong with no oil usage.
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Amsoil
    By  JAY,  a  Verified Buyer  on  January 06, 2026
    Pricy but suppose to be good synthetic oil.
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Great product
    By  DENNIS,  a  Verified Buyer  from  Safford, Az  on  January 05, 2026
    This is a great product,,, exceeded expectations
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Oil
    By  JAMES,  a  Verified Buyer  from  Texas  on  January 05, 2026
    Great Product and Service!!
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Diesel oil
    By  RICHIE,  a  Verified Buyer  from  Delaware  on  January 04, 2026
    Purchased for my tractor
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Diesel full synthetic oil
    By  Robbie,  a  Verified Buyer  from  Flin Flon Manitoba canada  on  December 24, 2025
    Everything shipped in a fantastic manner and packaging was great
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    2023 GMC 3500 Duramax
    By  BOB,  a  Verified Buyer  from  Vancouver B.C.  on  December 23, 2025
    I just finished my two free oil changes with the dealer and just did my third oil change myself with Amsoil. I changed the oil when the dash indicated I had 50% remaining life and will continue to change the oil at 50% remaining life. I believe GM recommends “Dextros” and Amsoil does not have that term on the bottle however, I believe Amsoil exceeds the GM spec and does not need to pay GM to advertise the Dextros name.
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Top Quality
    By  DAN,  a  Verified Buyer  on  December 22, 2025
    Top Quality oil
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  • 5 star rating
    EXCELLENT OIL
    By  HEATH,  a  Verified Buyer  from  CO  on  December 16, 2025
    Awesome oil for my 2021 6.6 Denali 2500HD ! BEEN USING IT FOR 3 YEARS!! VERY GOOD 💯 MY DIESEL LOVES IT AND I DO TOO.
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Quality Product
    By  KEVIN,  a  Verified Buyer  from  WI  on  December 16, 2025
    Since using this product my truck smokes less.
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Good product
    By  MARK,  a  Verified Buyer  on  December 15, 2025
    Seems to be good
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Simply the best oil
    By  MICHAEL,  a  Verified Buyer  from  Québec Canada  on  December 12, 2025
    outstanding protection for all weather condition!
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    WORKS AS PRESCRIBED
    By  PHILLIP,  a  Verified Buyer  from  Florida  on  December 12, 2025
    BEEN USING THIS FOR YEARS NOW IN MY 2015 SILVERADO 3500, I LOVE THE PRODUCT.
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Exceptional
    By  TODD,  a  Verified Buyer  from  Florida   on  December 10, 2025
    My Powerstroke diesels run extremely well using Amsoil. First one had 242k on it and is still running great. My son still has it and my second one has 140k on it. Still going strong. Go 10-12k per oil change.
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Amsoil signature series 15w 40 full synthetic oil
    By  BILLY,  a  Verified Buyer  from  Colcord Oklahoma   on  December 10, 2025
    I've been using the Amsoil sig. Series full synthetic 15 w 40 oil in my Duramax turbo diesel engine in 2 trucks I have owned, it is an excellent oil ,wouldn't use anything else ,I recommend this oil
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Simply the best
    By  RICKY,  a  Verified Buyer  from  San Diego  on  December 10, 2025
    This is the best oil out there
    Bottom Line
    Yes, I would recommend this to a friend.
    Was this review helpful?

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