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Customer Ratings & Reviews

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

Product code : DEOQT-EA

4.9 star rating Read 947 reviews

Customer Rating

4.9

89% would recommend

  • 5 902
  • 4 34
  • 3 3
  • 2 3
  • 1 5

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

4.9 star rating Based on 947 reviews
  • 5 star rating
    Amsoil the best
    By  JAY,  a  Verified Buyer  from  Lake Conroe  on  August 20, 2022
    Great product!
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Outstanding service, outstanding product
    By  BOBBY,  a  Verified Buyer  from  Missouri   on  August 16, 2022
    We’ve used the Signature Series diesel oil in all of our Ram & Ford trucks (and a Jeep GC) for 12+ years. Best oil on the market!
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Quality product
    By  DONALD,  a  Verified Buyer  from  Plainfield indiana   on  August 15, 2022
    Outstanding ordering process online, very quick delivery and outstanding Packaging. What I do wish is for the members they would at least throw in a funnel with each shipment, Even if it was just a paper funnel
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Signature Series Max-Duty Synthetic Diesel Oil 15W-40
    By  BARRY,  a  Verified Buyer  from  Mississippi Gulf Coast  on  August 11, 2022
    You definitely get what you pay for. This is the best oil that I've ever used in any of my vehicles.
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  • 5 star rating
    Diesel Oil
    By  WAYNE,  a  Verified Buyer  from  Southeast   on  August 11, 2022
    Great product, exactly what I was looking for.
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Luv it
    By  Dave,  a  Verified Buyer  on  August 08, 2022
    Use it in all of our vehicles. Been using it in my diesel trucks for years now and wouldn’t use anything else.
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Amazing product
    By  SCOTT,  a  Verified Buyer  from  Chevy 3500 Duramax   on  August 04, 2022
    Great product truck running better than ever.
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Excellent
    By  ANTHONY,  a  Verified Buyer  from  Maine  on  July 31, 2022
    always fantastic
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    BETTER SAFE THAN SORRY!
    By  RANDY,  a  Verified Buyer  from  Suwanee River  on  July 25, 2022
    I ordered this case for my diesel pickup just in case the rumors that diesel engine oil is soon to be unavailable along with DEF fluid too. Since I recently changed my oil and filter this case will last me well over a year when you consider the extended interval between changes using Amsoil.
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Smooth
    By  MIKE,  a  Verified Buyer  from  NJ   on  July 25, 2022
    I purchased the 5/40 for my 2019 ram 2500 6.7 . The engine runs so much better and cooler . I’m sold I will buy for next oil change
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Great Oil
    By  THOMAS,  a  Verified Buyer  from  Durham, NH   on  July 18, 2022
    I have looked up the reviews on the Internet and Amsoil comes out on top for the best in its class. I drive a diesel GMC 2500 and I want the best for my truck. AMSOIL 15W–40 and AMSOIL 5W–40 diesel winter time grade is the very best.
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Max duty diesel 15W40
    By  RANDALL,  a  Verified Buyer  from  Indiana  on  July 18, 2022
    Excellent product and fast shipping.
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    never going back
    By  ANTHONY,  a  Verified Buyer  from  Maine  on  July 18, 2022
    Have seen tremendous decreases in wear metals in oil analysis, as well as increases in fuel economy vs. the other synthetics I have tried. No need for them anymore.
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    great protection
    By  GREGORY,  a  Verified Buyer  from  arkansas  on  July 11, 2022
    will continue to run this oil as long as i have this truck hopefully another 200,000 miles plus.
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Best oil
    By  MICHELLE,  a  Verified Buyer  on  July 10, 2022
    Always use amsoil, so worth it and do to the fact we can get twice as many miles out of an oil change it’s more cost efficient. Also so much better for your diesel motors. 400,000 miles on our 2009 dodge 2500 Cummins 6.7. We put 500 miles a day on it pulling a trailer everyday loaded down. No leaks and don’t burn oil and still runs like a champ!
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Best out there
    By  DAVID,  a  Verified Buyer  from  Florida   on  July 08, 2022
    Beat oil out there!! Would definitely recommend this product to anyone
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Want netter fuel economy?
    By  BOB,  a  Verified Buyer  from  Houston   on  July 07, 2022
    This oil change I swapped to Amsoil. Just made a 500 mile vacation trip and was really happy to see that my 2020 Chevrolet 2500hd Duramax gained 2+ mpg after the oil change. I know that Amzoil doesn't make any mpg claims in their advertising but it sure showed up on my trip computer. With the current cost of diesel that makes my wallet a bit happier.
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 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.
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  • 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.
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  • 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.
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