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Customer Ratings & Reviews

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

Product code : DEOQT-EA

4.9 Read 495 reviews

Customer Rating

4.9

82% would recommend

  • 5 468
  • 4 23
  • 3 1
  • 2 1
  • 1 2

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

4.9 Based on 495 reviews
  • 5
    Best Oil
    By  LEROY,  a  Verified Buyer  from  Florida  on  February 26, 2021

    Describe the issue

    Reviewed the test results and I am satisfied the oil suits my needs. I do some heavy hauling and have used the oil since the truck was new. No issues.
    Bottom Line
    Yes, I would recommend this to a friend.
  • 5
    Diesel oil
    By  RYAN,  a  Verified Buyer  from  Florida   on  February 25, 2021

    Describe the issue

    Love amsoil the only oil I run in my diesel truck
    Bottom Line
    Yes, I would recommend this to a friend.
  • 5
    By  TODD,  a  Verified Buyer  on  February 24, 2021

    Describe the issue

    Bottom Line
    Yes, I would recommend this to a friend.
  • 5
    By  ADAM,  a  Verified Buyer  on  February 23, 2021

    Describe the issue

    Bottom Line
    Yes, I would recommend this to a friend.
  • 5
    Difference you can here
    By  STEPHEN,  a  Verified Buyer  on  February 23, 2021

    Describe the issue

    I was running another big name brand (T6) synthetic oil before, after switching to AMS oil I can here a difference in how the motor idles. Much smoother and quieter than before
    Bottom Line
    Yes, I would recommend this to a friend.
  • 5
    Best oil
    By  ALEC,  a  Verified Buyer  from  LA County   on  February 23, 2021

    Describe the issue

    Not much to say other then best oil on the market. I don’t use anything else. I use this in my 2001 Chevy Duramax that is always towing. 10/10 recommend
    Bottom Line
    Yes, I would recommend this to a friend.
  • 5
    GREAT PRODUCT / CUSTOMER SERVICE
    By  JAMES,  a  Verified Buyer  from  NORTH CAROLINA  on  February 21, 2021

    Describe the issue

    GREAT PRODUCT BEEN USING FOR YEARS WITH NO ISSUES, CUSTOMER SERVICE ALSO RECEPTIVE TO REQUESTS. I FEEL LIKE I KNOW THEM PERSONALLY
    Bottom Line
    Yes, I would recommend this to a friend.
  • 5
    By  MICHAEL,  a  Verified Buyer  from  Syracuse,NY  on  February 19, 2021

    Describe the issue

    Bottom Line
    Yes, I would recommend this to a friend.
  • 5
    #1
    By  HAROLD,  a  Verified Buyer  on  February 18, 2021

    Describe the issue

    I drive my diesel approx 4000 plus miles a week. Amsoil is without a doubt the best full synthetic oil and 2nd to none
    Bottom Line
    Yes, I would recommend this to a friend.
  • 5
    315,000 mi
    By  STEVEN,  a  Verified Buyer  from  Mass  on  February 17, 2021

    Describe the issue

    I've used this oil for years on my truck Duramax diesel 315,000 And the motors never been opened it's all I have to say
    Bottom Line
    Yes, I would recommend this to a friend.
  • 5
    By  VINCENT,  a  Verified Buyer  on  February 17, 2021

    Describe the issue

    Bottom Line
    Yes, I would recommend this to a friend.
  • 5
    Diesel oil
    By  MARK,  a  Verified Buyer  from  Iowa  on  February 15, 2021

    Describe the issue

    This oil I have been using ever since I got involved Amsoil I can’t tell you what the inside of the motor looks like because I’ve never had her taken one apart I had a Ford truck for the diesel Dodge Cummings now running it on 2014 Jeep Cherokee Limited and I never have had a problem with it I live in Iowa right now it’s 13 below zero and a cranks over like summer time.
    Bottom Line
    Yes, I would recommend this to a friend.
  • 5
    By  GALEN,  a  Verified Buyer  on  February 14, 2021

    Describe the issue

    Bottom Line
    Yes, I would recommend this to a friend.
  • 5
    The product I was looking for!
    By  LAYTON,  a  Verified Buyer  from  Beeville Texas   on  February 13, 2021

    Describe the issue

    So I’ve bought high end oils before like certified Labs and lubrication engineers Amsoil has surpassed those “competitors” I put this in quotations cause they truly don’t compare.
    Bottom Line
    Yes, I would recommend this to a friend.
  • 5
    Oil
    By  MARTIN,  a  Verified Buyer  from  La Pine OREGON  on  February 12, 2021

    Describe the issue

    This is my summer go to oil
    Bottom Line
    Yes, I would recommend this to a friend.
  • 5
    Amsoil... need I say more?
    By  JAKE,  a  Verified Buyer  from  Kentucky  on  February 08, 2021

    Describe the issue

    Best products on the market. A vehicle is an investment. Why not treat it like one? Use amsoil.
    Bottom Line
    Yes, I would recommend this to a friend.
  • 5
    Good Stuff
    By  MARK,  a  Verified Buyer  from  North East Oklahoma  on  February 08, 2021

    Describe the issue

    I've been using this product for 20 years, when I've seen the inside of other engines I use Amsoil in, I see the lack of wear. It must be doing the same thing inside my Cummins Diesel.
    Bottom Line
    Yes, I would recommend this to a friend.
  • 5
    Thick as Molasses....best diesel oil I have ever seen
    By  FRANK,  a  Verified Buyer  from  Denver, NC  on  February 07, 2021

    Describe the issue

    I bought it to run in a new diesel engine. I will run it hard and keep reviewing as I use it more and more.
    Bottom Line
    Yes, I would recommend this to a friend.
  • 5
    By  KIT,  a  Verified Buyer  from  Los Ojos NM  on  February 04, 2021

    Describe the issue

    I really enjoy this product. I can change my oil once a year or at 25,000 miles. In the long run this product saves me money.
    Bottom Line
    Yes, I would recommend this to a friend.
  • 5
    By  SCOTT,  a  Verified Buyer  on  February 03, 2021

    Describe the issue

    270,000 miles, still going strong
    Bottom Line
    Yes, I would recommend this to a friend.