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

Product code : DEOQT-EA

4.9 star rating Read 1,036 reviews

Customer Rating

4.9

90% would recommend

  • 5 988
  • 4 37
  • 3 3
  • 2 3
  • 1 5

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

4.9 star rating Based on 1,036 reviews
  • 5 star rating
    All I can say is Wow!!
    By  BRIAN,  a  Verified Buyer  from  Denver  on  October 01, 2023
    I use Amsoil in my cars and motorcycles and just tried in my semi truck. Can’t believe the difference over other major brands. I was disappointed major brands because I do long oil intervals changed with my ops filter and oil test every 25000 miles. The major brands I couldn’t keep the base up to where it needed to be. I will update on my lab test on Amsoil after 25k . Plus my fuel mileage went up one tenth. We will see if this continues
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Great oil for my Cummins
    By  KENNETH,  a  Verified Buyer  on  September 12, 2023
    Switched over from Royal Purple and could not be happier.
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Great diesel oil
    By  DANO,  a  Verified Buyer  on  September 11, 2023
    All usual Amsoil doesn't disappoint. Great oil for Ram 6.7, and there deliveries rapid. Will always buy my oils from Amsoil
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Good stuff
    By  RONNIE,  a  Verified Buyer  on  September 08, 2023
    Worth the money
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Long lasting
    By  LUCY,  a  Verified Buyer  from  Killeen, Texas  on  September 08, 2023
    Quality stuff here. Long lasting good quality oil. A bit pricey but you get what you pay for
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Diesel Oil 5W-40
    By  RICK,  a  Verified Buyer  from  MA  on  September 06, 2023
    Use Amsoil Signature Series Max-Duty Synthetic Diesel Oil 5W-40 for every oil change. Rated the best for Cummins diesels.
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Backup for m 3 diesels
    By  Steven,  a  Verified Buyer  from  California  on  September 03, 2023
    This is just outstanding oil.
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Car
    By  ROBERT,  a  Verified Buyer  from  Fairview   on  September 03, 2023
    Car seems to run more smoothly
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Ram 2500 diesel
    By  MARK,  a  Verified Buyer  from  Austin, Texas   on  September 01, 2023
    Good stuff!
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Just buy it
    By  MIKE,  a  Verified Buyer  on  August 30, 2023
    Surprised, a lot smother and quitter engine
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Using this oil for many years
    By  MAHRAD,  a  Verified Buyer  from  Central Florida  on  August 27, 2023
    I have been using the 15 W 40 Amsoil diesel oil for many years on different GMC Duramax diesels. All on lower mileage trucks. It is a good durable oil. No burning of loss of oil. No engine mechanical issues. I perform the oil changes myself. Libricity of the old oil is very good. The 2.5 gallon container is difficult to handle without spilling. I recommend getting it in quart size containers. I recommend the oil.
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Fast Delivery
    By  CRISANTO,  a  Verified Buyer  from  Sammamish Wa  on  August 26, 2023
    Great oil at a good price. Overnight delivery
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 4 star rating
    The trip
    By  KK,  a  Verified Buyer  from  Plymouth wi to masa AZ   on  August 20, 2023
    I use 5W-40in my 3VW TDI WHEN I TOOK a trip to AZ 122 temp I seen my oil in my Commons diesel pick up to literally evaporate the oil. In Wisconsin, my truck doesn't use any oil. In outer Arizona, it evaporates the oil.
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Amsoil 5-40 oil for diesels
    By  Robert,  a  Verified Buyer  from  FL  on  August 19, 2023
    This is the only oil that I have found that does not cause me problems with my diesel exhaust filter. No regens since I have been running it. Ram 1500 ecodiesel.
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    The REAL Deal!!!
    By  JOHN,  a  Verified Buyer  from  Texas   on  August 08, 2023
    We used to run Amsoil in oil fleet vehicles years ago, don’t know why they got away from it. Anyways, I run a 2019 Chevy DRW, bought it with 92k. First oil change I did, went with Amsoil Signature. Went to oil change interval recommended by GM (approx 7k miles). I tow a 14-16k 5th wheel light/ moderate distances several times a year. Had the oil tested by a 3rd party, analysis came back I could go to 10k. Levels tested still well above normal for oil with the mileage and oil filter was still good. Don’t know how they could test that, but they did. Went 10k miles on next interval, had it tested again, same tests, same company. Analysis came back less than before, but still above acceptable levels according to them. Have a sample from 15k miles waiting to be tested. I can say, all of my vehicles now use Amsoil signature!
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    80 kw ohan cummins generator
    By  GARY,  a  Verified Buyer  from  dauphin island  on  August 06, 2023
    run this in my generator for a peace of mind knowing it's the best
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  • 5 star rating
    Best oil
    By  JOSE,  a  Verified Buyer  from  Round Rock Tx  on  August 05, 2023
    Best oil
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Has stood the test of time
    By  JERRY,  a  Verified Buyer  on  August 03, 2023
    I have been using this in my truck for 27 years and my truck still runs great. 352,000 miles.
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Outstanding
    By  KEVYN,  a  Verified Buyer  from  Texas   on  August 02, 2023
    This exact oil saved a motor that blew a head gasket and lost all but 2 of the 14 quarts. Ford mechanic was amazed at how good the cylinders still looked. He stated he had many that had the same problems but all the others the motor was trash. Mine just had to have a new head gasket engine flush fresh oil and antifreeze. Then was back on the road.
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Best stuff out there
    By  DAVID,  a  Verified Buyer  from  Florida   on  August 02, 2023
    This oil is the only oil I’ll use on my diesel truck!! She’s 11 yes old and runs like a champ
    Bottom Line
    Yes, I would recommend this to a friend.
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