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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 923 reviews

Customer Rating

4.9

89% would recommend

  • 5 878
  • 4 34
  • 3 3
  • 2 3
  • 1 5

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

4.9 star rating Based on 923 reviews
  • 5 star rating
    Best oil you can buy.
    By  JOHN,  a  Verified Buyer  from  Long Island NY  on  November 28, 2022
    Anything Ams is too quality top notch beats everyone else. If you don't believe me get an couple old pans and an OUTDOOR camp stove. Put AMS against anything else and I garantee it will shock you. Be careful. I simply won't put anything else in my vehicles or toys.
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Signature Series provides a noticeable difference
    By  AUSTIN,  a  Verified Buyer  on  November 27, 2022
    I have used other brands’ cheaper full synthetic engine oils in the past, but after switching to Signature Series oil in my ‘97 12v, I have noticed quieter and smoother engine operation from the oil change alone. My truck is going on 400k miles, and it’s safe to say it will the Signature Series treatment going forward.
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Amsoil synthetic oil
    By  DWAYNE,  a  Verified Buyer  from  Terrace BC  on  November 25, 2022
    I broke my 2003 duramax in and switched to Amsoil 15-40 and now have over 800,000kms on it with out ever removing the valve covers and it is still running strong
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Signature series max duty
    By  SHANE,  a  Verified Buyer  on  November 22, 2022
    I have a lifted 2014 ram 2500. since I start using amsoil it runs smoother and quieter for longer. I 100% recommend them
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    2011 GMC SIERRA 3500HD Diesel oil change
    By  TONY,  a  Verified Buyer  from  Arizona  on  November 21, 2022
    Ordering from AMSOIL is always super fast shipping and the best quality of oil out there. I run it in all my Vehicles which is including my 18 turbo RZR and my built Harley.
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Diesel oil
    By  JAMES,  a  Verified Buyer  from  Pa  on  November 13, 2022
    Been running this oil from new purchase 2016 of truck
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Beat oil out there
    By  DAVID,  a  Verified Buyer  from  Florida  on  November 06, 2022
    This is the best oil out there! I won’t use anything but amsoil product in my truck and car
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Good quality oil
    By  DOUGLAS,  a  Verified Buyer  from  North Texas  on  November 01, 2022
    I like Amsoil's quality and their constant testing.
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Great oil
    By  PAUL,  a  Verified Buyer  on  October 31, 2022
    We go 8000 mi. Between oil change now
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Great oil, and it was in stock
    By  CHRIS,  a  Verified Buyer  on  October 27, 2022
    Like the title says great oil, and it was in stock when I ordered it, and arrived with in a week of ordering. Planned on changing to Amsoil, and when the stores supply of the other brand I had used I changed.
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Flip
    By  PHILLIP,  a  Verified Buyer  from  Pennsylvania   on  October 25, 2022
    I have your products in racing with great success. The diesel oil is for my wife’s truck which she makes trips to Tennessee, Missouri,Kentucky,& Texas pulling a43 ft horse trailer I like make sure things are protected the best way possible I believe Amsoil does that.
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Best oil on the market!
    By  BURT,  a  Verified Buyer  from  Lancaster, PA  on  October 22, 2022
    Best oil on the market! You can actually feel the difference when you put some between your finger tips. I trust this oil in my '96 Powerstroke for a year at a time. (I don't put a lot of miles on it in a year).
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Rotella WHO????
    By  JASON,  a  Verified Buyer  from  NJ  on  October 17, 2022
    1990 Jeep YJ 4.2 I run 5w-40 (winter) 5w-50 (summer) NJ I was a Rotella user for years. This engine needs dino oil because of its high zinc content. Amsoil Diesel oil is just plain better imo. Cold starts are quieter. This motor has been bored & stroked to 4.7ci with a mild comp cam. I have higher oil pressure at idle and at speed than Rotella. 10 more psi at 55mph. and around 5-7 psi increase over Rotella at idle. Gas mileage has improved as well. The motor just seems to run smother. I was hesitant to switch but I'm glad I did. Sorry Rotella. But the improvement from Amsoil is obvious. Thank you Amsoil.
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Only Trust Amsoil Products
    By  Dusty,  a  Verified Buyer  from  Albuquerque  on  October 15, 2022
    Always use Amsoil in my diesel truck, tractor, cars, small engines , and air compressors. Nothing better.
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Signature Max-Duty Synthetic Diesel Oil
    By  FRANK,  a  Verified Buyer  from  Nevada  on  October 14, 2022
    Really great for my 1-ton Ram.....
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Diesel oil
    By  MICHAEL,  a  Verified Buyer  from  Ohio  on  October 14, 2022
    I’ve been using in my Ram EcoDiesel for 115,000 miles. SeemS to be working well time will tell!
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Diesel oil
    By  DAVID,  a  Verified Buyer  on  October 10, 2022
    Awesome oil
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Doing its thing for years...
    By  JEFF,  a  Verified Buyer  from  Turtletown, TN  on  October 09, 2022
    Been a long time user and most recently in a 2015 Ram eco diesel. About 107,000 miles on it and has never leaked a drop, used a drop nor had any oil\engine related issues. Same with prior 1-ton Dodge dually and Ford F350 diesels. Shipping has always been quick and picking up from Orlando, FL on visits I've found the order ready and the folks helpful.
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Awesome
    By  RADU,  a  Verified Buyer  from  Portland Oregon   on  October 08, 2022
    Very good quality, I use on my 21 silverado duramax, and I love it, I recommend this product
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Signature oil
    By  STEVE,  a  Verified Buyer  from  Vernon Ct.  on  October 05, 2022
    One and done per year. I like their products across the board.
    Bottom Line
    Yes, I would recommend this to a friend.
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