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

Product code : DMEQT-EA

4.9 star rating Read 1,543 reviews

Customer Rating

4.9

92% would recommend

  • 5 1478
  • 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 1,543 reviews
  • 5 star rating
    Would buy again
    By  Kodiak,  a  Verified Buyer  from  Pleasant Hill Mo.  on  March 13, 2018
    My Diesel runs smoother and quieter
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Great all around product.
    By  McKittrick,  a  Verified Buyer  from  Montana  on  March 09, 2018
    I never knew you could see the difference in oil. I switched to amsoil a few months ago. I noticed easier starting in sub zero weather, and a slight increase in fuel mileage. I was running a synthetic before. Amazing.
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Superior performance
    By  celtic,  a  Verified Buyer  from  New Bern NC  on  March 06, 2018
    I became aware of And oil in 1985. I knew how good synthetic oil was as my older brother was a petroleum engineer and he declared that synthetic oil would soon be the dominant motor oil. I had my brother run some tests on a quart of And oil and he reported that the stuff was off the charts. He and I became long time customers. I have never had any type of engine failure due to poor oil performance.
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Longevity
    By  Rosie,  a  Verified Buyer  from  Saint Cloud, Fl  on  March 05, 2018
    Installed AMSOIL in my old Chev Diesel. Changed the filter every 5000 miles . Checked quality of oil each time. At 20000 miles the oil was still good. Amen. This was at 100000 miles and used a quart every 3000 miles .mwhrn traded atb441000 miles it used only 1/2 guard in 10000 miles . Had an old 99 suburban diesel bought used. Was up to 1 quart every 4500 miles when traded at 352000 miles.
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Fabulous lubrication
    By  7Trumpets 42,  a  Verified Buyer  from  Loveland, CO  on  March 01, 2018
    I am having regular oil analysis with each 10K mile change. Engine metals are lower than average for the V-M 3. 0. I couldn't be happier with this signature Amsoil product!
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 4 star rating
    Top Performer
    By  Hauss,  a  Verified Buyer  from  Phoenix, AZ  on  February 26, 2018
    I've been using Amsoil lubricants for decades. I'm loyal to the brand. I've been with Amsoil through the good times, and one of their bad times (back in the eighties). I've run Amsoil in motorcycles, cars, trucks, boats, high-performance engines, and factory daily drivers. I have extensive experience in engine machining/building, and I've seen, first hand, how Amsoil provides performance and durability to engines that push their design limits. Recently I bought a 2017 F250 with the PowerStroke diesel, and I got to reading about the particulate filters, and how oils not approved by Ford could cause premature clogging of the DPF, and possibly void the manufacturers warranty. Oils manufactured to the CK-4 spec initially resulted in premature wear in 2017 PowerStroke engines, so Ford released their own specification, WSS-M2C171-F1, and instructed owners to run CJ-4 oils until approved CK-4's were available. Since then several products have been approved by Ford for use in PowerStrokes, but concerned about the performance of the available CK-4 oils, and curious about how Amsoil's Signature Series Max-Duty Diesel Engine Oil compared to them, I submitted a couple of samples to the guy who runs the 540 RAT Blog for testing. The Amsoil product tested superior to all others tested to date, beat only by another of Amsoil's own CI-4 spec diesel engine oil. I wasn't surprised by that, based on my experience, but I was surprised to see a conventional CK-4 oil approved by Ford that also meets WSS-M2C171-F1, performed as well as Amsoil's Sig Series Max-Duty, and costs about half what Amsoil's product does. I would love for Amsoil to explain why their product is still superior to that competing product, even though they performed so similarly in 540 Rat's test. At thirteen quarts, half the price is quite a savings. Is it really worth the price?
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Great stuff
    By  Russ,  a  Verified Buyer  from  Lompoc ca  on  February 25, 2018
    Great oil for my 2500 Jd
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    I am going to continue to buy this product
    By  Rock,  a  Verified Buyer  from  New Mexico  on  February 24, 2018
    This product is great. I have ran this product the last 15,000 miles. My trucks starts smooth after sitting for a week in the cold weather of northern NM. Never misses a beat either. Would recommend to any diesel owner out there.
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Consistently Reliable
    By  RAV,  a  Verified Buyer  from  Jacksonville, FL  on  February 23, 2018
    Since 2010 I've been using Amsoil fluids and filters in my Dodge Ram 2500 Cummins Diesel and as a result, have had no engine or transmission failures. The diesel engine oil & filter are both 25,000 mile change frequency; Amsoil does cost more, but you'll save money in the long run with zero failures and extended periods between scheduled maintenance. I also ran Amsoil transmission fluid in the same truck for 70,000+ miles with no slippage, and always witness iyuyreliable, positively locked shifts.
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Excellent product! Use in every diesel I own
    By  Bryce,  a  Verified Buyer  from  Coudersport Pennsylvania  on  February 20, 2018
    I've used this product as well as many other amsoil products in many trucks and pieces of equipment and they are superior to any other on the market. Much smoother running with lower temps and increased mileage.
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    I would buy again
    By  Bentley,  a  Verified Buyer  from  IL  on  February 17, 2018
    Feels like my trtuck runs a lot smoother
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    I buy AMSOIL
    By  sawdust,  a  Verified Buyer  from  charlotte nc  on  February 13, 2018
    I have used AMSOIL for over 30 years great stuff!
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 4 star rating
    Only oil go my things!
    By  Cujo,  a  Verified Buyer  from  Spyhill SK  on  February 13, 2018
    Duramax seams to like it, oil samples great @ 10000km, filter change and re sample @ 20000km!
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    I will be purchasing again
    By  Pete,  a  Verified Buyer  from  Tunkhannock PA  on  February 13, 2018
    Love using the best protection available for my Chevy 6.6 that I work hard everyday and with 123,000 not a single hiccup.
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    I would and do buy it all the rime
    By  Chuck,  a  Verified Buyer  from  Northern Alberta canada  on  February 10, 2018
    ??
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    I am a true believer
    By  Stan H.,  a  Verified Buyer  from  West Virginia  on  February 06, 2018
    I have used amsoil for years in my 6.7 cummins diesel and it has never failed to deliver . I recently swithed to the new 6x signature 5W-40 and I noticed that my oil pressure went up one pound and my fuel mileage went up one mile per hour also . Now to some this may not be a big deal but it adds up over time and that it is giving me better pressure at the same time only goes toward helping to further protect my engine. with the increased wear protection quality and potential I look forward to many more years of faithful performance from amsoil oil just like this .
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Only oil I use
    By  Charlie,  a  Verified Buyer  from  Va  on  February 06, 2018
    Only use the truck to tow keeps oil temp down
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Love my truck
    By  Bill,  a  Verified Buyer  from  Louisiana  on  January 27, 2018
    The oil in my 199 F-250 SD with 7.3 diesel, bought new, use to get its oil changed every 3-5K miles for the first 6 oil changes. Then the switch was made to Amsoil Synthetic, with Amsoil oil filter. The oil still looks new after the first 3-4K miles and is changed every 10K miles. Although I have had no problem with this vehicle related to lubrication, the vehicle may be considered low mileage with 262,000 miles and o8il consumption has been greatly decreased. Love this oil.
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Great oil for cold winter
    By  Greg,  a  Verified Buyer  from  NH  on  January 26, 2018
    I have used this oil in my Silverado Duramax in cold weather and it helps with cold starts and driveability during long warm-up time. The engine gets lubrication almost immediately upon startup and sounds like it is running on a summer day. Amsoil is the best!
    Bottom Line
    Yes, I would recommend this to a friend.
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  • 5 star rating
    Great results
    By  Brennon,  a  Verified Buyer  from  Gatlinburg TN  on  January 24, 2018
    Before using this product in a 2015 Silverado 2500 I had consumption of standard oil. Truck was using 1 quart of oil per 5000 miles. After switching to this product I have not experienced any consumption.
    Bottom Line
    Yes, I would recommend this to a friend.
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