Skip to Main Content
Shop by Vehicle

Customer Ratings & Reviews

AMSOIL Signature Series 15W-40 100% Synthetic Max-Duty Diesel Oil

Product code : DMEQTC-EA

4.9 star rating Read 1,537 reviews

Customer Rating

4.9

92% would recommend

  • 5 1472
  • 4 45
  • 3 9
  • 2 3
  • 1 8

AMSOIL Signature Series 15W-40 100% Synthetic Max-Duty Diesel Oil

4.9 star rating Based on 1,537 reviews
  • 5 star rating
    Oil
    By  JAMES,  a  Verified Buyer  from  Wisconsin   on  December 28, 2024
    Expensive oil but good . I run it in my 12 valve Cummins in the wi winters
    Bottom Line
    Yes, I would recommend this to a friend.
    Was this review helpful?
  • 5 star rating
    What a Great Buying Experience
    By  NICK,  a  Verified Buyer  from  Florida  on  December 26, 2024
    I have been changing oil on multiple vehicles for over 50 years. After much research I decided to switch to Amsoil starting with my 2025 2500 GMC AT4X Duramax. My first purchase was on line from Amsoil and my second purchase was from a local distributor. Both experiences were flawless and with the online purchase I never left my house and the delivery was quick and on time. I will continue to purchase online as the entire delivery process was as promised. The packaging was as expected. No complaints.
    Bottom Line
    Yes, I would recommend this to a friend.
    Was this review helpful?
  • 5 star rating
    275k and going strong
    By  GREG,  a  Verified Buyer  from  NY  on  December 26, 2024
    I have been using this product since my GMC w/ diramax was new in 2012. I change the filter and top off at 7500 miles and change oil and filter at 15000. The truck now has 275k without any lubrication issues.
    Bottom Line
    Yes, I would recommend this to a friend.
    Was this review helpful?
  • 5 star rating
    Great product!
    By  STEWART,  a  Verified Buyer  from  Anchorage, AK  on  December 24, 2024
    Great product! No more ticking sound!
    Bottom Line
    Yes, I would recommend this to a friend.
    Was this review helpful?
  • 5 star rating
    Companion to EA098 filter
    By  GARY,  a  Verified Buyer  from  Charleston, SC  on  December 24, 2024
    To use this oil in conjunction with the EA098 filter and change every 15,000 miles. I feel confident this will help protect my 6.7L diesel engine better than any other products.
    Bottom Line
    Yes, I would recommend this to a friend.
    Was this review helpful?
  • 5 star rating
    Long lasting
    By  TIM,  a  Verified Buyer  from  Texas  on  December 23, 2024
    Running this oil for a while. Ran to 10,000 miles and sent sample in and they said to go another 5,000. I’m satisfied. Also run Amsoil in the Harleys. Definitely worth the money.
    Bottom Line
    Yes, I would recommend this to a friend.
    Was this review helpful?
  • 5 star rating
    2002
    By  RICK,  a  Verified Buyer  from  PNW  on  December 23, 2024
    I attribute my 265,000 plus miles on my 2002 chev. 2500 HD 6.6 to AMSOIL I use the 1540 synthetic and the AMSOIL oil filter I get 8000 plus miles between oil changes saves me money
    Bottom Line
    Yes, I would recommend this to a friend.
    Was this review helpful?
  • 5 star rating
    Best Product
    By  LANCe,  a  Verified Buyer  from  Florida  on  December 18, 2024
    Best oil and product been using since I purchase my truck
    Bottom Line
    Yes, I would recommend this to a friend.
    Was this review helpful?
  • 5 star rating
    Best oil I've ever used
    By  RICH,  a  Verified Buyer  on  December 15, 2024
    Amsoil is the best oil I have ever used in my diesel truck. I love the protection it gives my engine. Runs great
    Bottom Line
    Yes, I would recommend this to a friend.
    Was this review helpful?
  • 5 star rating
    2000 Ford Diesel 297000 miles
    By  Old 7.3 Diesel ,  a  Verified Buyer  from  Lincolnton NC  on  December 12, 2024
    Been running Amsoil 15-40W fully synthetic since 70000 miles. Almost 300000 25 years old in January. Motor still runs like a scalded dog. No oil related problems. Change oil once a year. Only had to replace injectors and glow plugs around 265000. Not really any engine problems due to oil.
    Bottom Line
    Yes, I would recommend this to a friend.
    Was this review helpful?
  • 5 star rating
    First time user
    By  DAN,  a  Verified Buyer  from  Fountain,CO  on  December 11, 2024
    First time user, not sure but heard this oil is the best
    Bottom Line
    Yes, I would recommend this to a friend.
    Was this review helpful?
  • 5 star rating
    Great oil I run it in everything
    By  BLAIR,  a  Verified Buyer  from  Alberta  on  December 10, 2024
    Just changed the oil for the first time in the new truck. Ran ams oil in all my small engines and hasn’t disappointed. Plus free stickers in every box is a huge bonous for us oil and gas workers
    Bottom Line
    Yes, I would recommend this to a friend.
    Was this review helpful?
  • 5 star rating
    Haven't used it yet
    By  ROBERT,  a  Verified Buyer  from  Cross  on  December 10, 2024
    Good delivery service
    Bottom Line
    Yes, I would recommend this to a friend.
    Was this review helpful?
  • 5 star rating
    The big switch
    By  BRIAN,  a  Verified Buyer  from  NJ  on  December 09, 2024
    I bought a 2008 Ram 2500 6.7L recently. This is my first diesel. Everyone that I have spoken to talks about the quality of Amsoil's products. I decided to become a preferred customer and switch the truck over to Amsoil. I hope this decision gives me hundreds of thousands of miles of life in this truck.
    Bottom Line
    Yes, I would recommend this to a friend.
    Was this review helpful?
  • 5 star rating
    Amassing product
    By  COLE,  a  Verified Buyer  from  Montana  on  December 09, 2024
    This is all I will ever run it’s worth the money I’m a preferred customer and everyone that I have turned onto Amsoil after an engine flesh has said their vehicle has never ran better smoother and they could feel the power increase. I would love to become a dealer one day and convert every oil in my truck to amsoil best product I have ever used
    Bottom Line
    Yes, I would recommend this to a friend.
    Was this review helpful?
  • 5 star rating
    Diesel oil
    By  BRIAN,  a  Verified Buyer  on  December 08, 2024
    I love this oil. When it's cold out the engine spins over just like it does it the summer.
    Bottom Line
    Yes, I would recommend this to a friend.
    Was this review helpful?
  • 5 star rating
    AMSOIL
    By  ABE,  a  Verified Buyer  on  December 07, 2024
    I highly recommend AMSOIL for our vehicles. it’s a premium quality oil.and I can be confident on road trips that my engine will be well lubricated.
    Bottom Line
    Yes, I would recommend this to a friend.
    Was this review helpful?
  • 5 star rating
    Great for the 1025R
    By  Dade22,  a  Verified Buyer  on  December 06, 2024
    Dumped the factory oil from my 2024 John Deere 1025r. Maintenance schedule says 200 hours for the first change. No way. I pulled it at 50 hours. It was dark. Some wear metals as expected. I swapped it over to Amsoil 15w-40 Signature Series. First thing I noticed was how easy it was to start and the noise level even dropped. The engine actually seemed to run smoother. I’m a maintenance fanatic. I believe frequent oil changes at the beginning. I will probably pull this out at the 100 hours and then just change it once a year afterwards.
    Bottom Line
    Yes, I would recommend this to a friend.
    Was this review helpful?
  • 5 star rating
    So far so good 👍
    By  MATT,  a  Verified Buyer  from  New Hampshire  on  November 29, 2024
    I have always used amsoil products and will continue to use them, this diesel oil was exactly what my high horsepower heavy hauling Duramax needed
    Bottom Line
    Yes, I would recommend this to a friend.
    Was this review helpful?
  • 5 star rating
    Signature Series 15w40 Syntheric Max Duty Diesel oil
    By  ROBERT,  a  Verified Buyer  on  November 24, 2024
    the Best oil around. Engine seems to run quieter. Also improved gas millage
    Bottom Line
    Yes, I would recommend this to a friend.
    Was this review helpful?