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AMSOIL 15W-40 Heavy-Duty Diesel and Marine Oil
Product code : AMEQT-EA
AMSOIL 15W-40 Heavy-Duty Diesel and Marine Oil
Product code : AMEQT-EA
Current price:
$16.59
Retail Price
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Estimated delivery by Mon, Jun 8
to Columbus - 43215.
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- Recommended for applications specifying API CI-4+ and prior specifications
- Controls soot and wear
- Reduces oil consumption and emissions
- Delivers maximum engine protection over extended drain intervals
- Provides outstanding protection and performance in temperature extremes
- Try Signature Series Max-Duty 15W-40 for a serious upgrade
-
We offer easy returns for customers. If your product is unused and unopened, you may return it within 30 days for a full refund of the purchase price. View full AMSOIL Return Policy.
-
We accept Visa, Mastercard, American Express, Discover and PayPal, and provide secure checkout and encrypted payment processing.
About this item
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Premium diesel oil providing excellent performance in diesel engines where highly effective control of wear and deposits is vital. Built with heavy-duty dispersant/detergent additives with 12 TBN, Synthetic Heavy-Duty Diesel & Marine Oil neutralizes acids and controls soot thickening from EGR and blow-by to protect against corrosion, cylinder bore polishing (wear) and varnish/sludge deposits. It resists heat and breakdown and is formulated for extended drain intervals.
See the product data sheet for full details.
CONTROLS SOOT AND WEAR
- Neutralizes acids and controls soot thickening to protect against corrosion, wear, varnish and sludge deposits
- Reduces oil consumption and emissions
- Delivers maximum engine protection over extended drain intervals
EXCELS IN EXTREME TEMPERATURES
- Provides outstanding protection and performance in temperature extremes
- Resists heat and breakdown better than conventional oils
- Eases cold-weather starting and provides vital startup lubrication
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star rating
The best oil for old dieselsBy MIKE78, a Verified Buyer from Dixon, CA on June 01, 2026The 15w-40 heavy duty diesel and marine oil is the only oil I’d use in my old Dodge Cummins 24 valve with a flat tappet valve train. The newer CK-4 rates diesel engine oils are designed for the newer emissions engines with a DPF and roller valve trains. The CK-4 oils don’t have the additive package needed to protect the older diesels because those very lubrication & detergent additives, zinc, phosphorus, & calcium, will damage the DPF and emissions equipment on newer diesels. Oil manufacturers will say the newer CK-4 and higher oils are backwards compatible, but they truly aren’t. This is coming from a guy that has an AA degree in diesel mechanics, 37 years working for a heavy equipment dealership, 17 years as a HD mechanic, 3 years as a T/C which also involved managing the oil lab, and the last 17 as a product support rep. I truly hope Amsoil continues to keep the HD 15w-40 diesel & marine oil in their line up.Bottom LineYes, I would recommend this to a friend.Was this review helpful?
-
star rating
Has the correct API rating compared to other oilBy HABEEB, a Verified Buyer from AZ on February 27, 2026My last conversation with one of your reps. Im so pleased to hear that your corporation has a location now in Dubai and Iran. Hopefully not Israel.Bottom LineYes, I would recommend this to a friend.Was this review helpful?
-
star rating
The best diesel oil for pre-emissions vehicles.By HUNTER, a Verified Buyer on November 12, 2025Got turned into this oil by a master mechanic for Detroit Marine Diesel engines. I have never used anything else in my duramax and recommend it to anyone that doesn’t have a DPF. I use oil analysis and the results wish for themselves.Bottom LineYes, I would recommend this to a friend.Was this review helpful?
-
star rating
All I use in my pre DPF Duramax trucksBy DAN, a Verified Buyer from CA on October 27, 2025This oil has a TBN of 12 and it's all I use in my Duramax LBZ trucks. Has a higher ash content not suitable for DPF trucks. Read the Amsoil article about the million mile Duramax.Bottom LineYes, I would recommend this to a friend.Was this review helpful?
-
star rating
HD Diesel 15w-40 best for older diesel engineBy MIKE, a Verified Buyer from California on August 26, 2025I’ve been using the HD Diesel & Marine oil in my 2002 2500 Dodge Cummins, which is a flat tappet cam follower system. I trust the high zinc and other additives that are used in the older CG-4 & plus classification oils and Amsoil is at the top in quality. I don’t trust the “backwards compatible” statement in the use of the newer CK classification. These newer engines with DPF’s have to run the CK classification due to the ash from what oil gets by the rings and gets burned in the combustion cycle. The older high zinc and calcium additives cause problems in the current diesel emissions system, but you have to understand, these newer diesel engines are engineered for these oils. They are all running roller cam followers & roller tappets with less friction than my older flat tappet & cam follower cummins. I’m so thankful that Amsoil still offers the 15w-40 HD Diesel & Marine oil.Bottom LineYes, I would recommend this to a friend.Was this review helpful?
-
star rating
WalterBy YAREMCHUK, a Verified Buyer on August 01, 2025Very good qualityBottom LineYes, I would recommend this to a friend.Was this review helpful?
-
star rating
Great Motor Oil.By ALVIN, a Verified Buyer from 80421 on July 05, 2025I have used this motor oil in a 2001 Ford F250. I have pulled a 38 foot fifth wheel among other things and it has never used a drop of oil. I change it once a year and I have been very impressed with the results.Bottom LineYes, I would recommend this to a friend.Was this review helpful?
-
star rating
best oil I ever ran in a motor,By GEORGE, a Verified Buyer on June 25, 2025great service and great product. don't use anything but amsoilBottom LineYes, I would recommend this to a friend.Was this review helpful?
-
star rating
WalterBy YAREMCHUK, a Verified Buyer from Orland Park,IL on April 14, 2025Good quality,recommendedBottom LineYes, I would recommend this to a friend.Was this review helpful?
-
star rating
amazing qualityBy ERIC, a Verified Buyer on February 11, 2025i did a full fluid flush being , front diff , engine oil , transmission, t case , rear diff . the fluid quality is out standing as for the truck now runs and rolls like new and much more quiet as before. it’s clearly more happy that it was now that all fluids are done. the g56 manual trans shifts like new now and it’s got 140k on it . highly highly recommend AMS oil. i need to do a coolant flush next so if they sell coolant i will be buying it soon. 10/10 starsBottom LineYes, I would recommend this to a friend.Was this review helpful?
-
star rating
Data Bulletins-
- Recommended for applications specifying API CI-4+ and prior specifications
- Controls soot and wear
- Reduces oil consumption and emissions
- Delivers maximum engine protection over extended drain intervals
- Provides outstanding protection and performance in temperature extremes
- Try Signature Series Max-Duty 15W-40 for a serious upgrade
-
We offer easy returns for customers. If your product is unused and unopened, you may return it within 30 days for a full refund of the purchase price. View full AMSOIL Return Policy.
-
We accept Visa, Mastercard, American Express, Discover and PayPal, and provide secure checkout and encrypted payment processing.
-
Premium diesel oil providing excellent performance in diesel engines where highly effective control of wear and deposits is vital. Built with heavy-duty dispersant/detergent additives with 12 TBN, Synthetic Heavy-Duty Diesel & Marine Oil neutralizes acids and controls soot thickening from EGR and blow-by to protect against corrosion, cylinder bore polishing (wear) and varnish/sludge deposits. It resists heat and breakdown and is formulated for extended drain intervals.
See the product data sheet for full details.
CONTROLS SOOT AND WEAR
- Neutralizes acids and controls soot thickening to protect against corrosion, wear, varnish and sludge deposits
- Reduces oil consumption and emissions
- Delivers maximum engine protection over extended drain intervals
EXCELS IN EXTREME TEMPERATURES
- Provides outstanding protection and performance in temperature extremes
- Resists heat and breakdown better than conventional oils
- Eases cold-weather starting and provides vital startup lubrication
-
-
-
star rating
The best oil for old dieselsBy MIKE78, a Verified Buyer from Dixon, CA on June 01, 2026The 15w-40 heavy duty diesel and marine oil is the only oil I’d use in my old Dodge Cummins 24 valve with a flat tappet valve train. The newer CK-4 rates diesel engine oils are designed for the newer emissions engines with a DPF and roller valve trains. The CK-4 oils don’t have the additive package needed to protect the older diesels because those very lubrication & detergent additives, zinc, phosphorus, & calcium, will damage the DPF and emissions equipment on newer diesels. Oil manufacturers will say the newer CK-4 and higher oils are backwards compatible, but they truly aren’t. This is coming from a guy that has an AA degree in diesel mechanics, 37 years working for a heavy equipment dealership, 17 years as a HD mechanic, 3 years as a T/C which also involved managing the oil lab, and the last 17 as a product support rep. I truly hope Amsoil continues to keep the HD 15w-40 diesel & marine oil in their line up.Bottom LineYes, I would recommend this to a friend.Was this review helpful?
-
star rating
Has the correct API rating compared to other oilBy HABEEB, a Verified Buyer from AZ on February 27, 2026My last conversation with one of your reps. Im so pleased to hear that your corporation has a location now in Dubai and Iran. Hopefully not Israel.Bottom LineYes, I would recommend this to a friend.Was this review helpful?
-
star rating
The best diesel oil for pre-emissions vehicles.By HUNTER, a Verified Buyer on November 12, 2025Got turned into this oil by a master mechanic for Detroit Marine Diesel engines. I have never used anything else in my duramax and recommend it to anyone that doesn’t have a DPF. I use oil analysis and the results wish for themselves.Bottom LineYes, I would recommend this to a friend.Was this review helpful?
-
star rating
All I use in my pre DPF Duramax trucksBy DAN, a Verified Buyer from CA on October 27, 2025This oil has a TBN of 12 and it's all I use in my Duramax LBZ trucks. Has a higher ash content not suitable for DPF trucks. Read the Amsoil article about the million mile Duramax.Bottom LineYes, I would recommend this to a friend.Was this review helpful?
-
star rating
HD Diesel 15w-40 best for older diesel engineBy MIKE, a Verified Buyer from California on August 26, 2025I’ve been using the HD Diesel & Marine oil in my 2002 2500 Dodge Cummins, which is a flat tappet cam follower system. I trust the high zinc and other additives that are used in the older CG-4 & plus classification oils and Amsoil is at the top in quality. I don’t trust the “backwards compatible” statement in the use of the newer CK classification. These newer engines with DPF’s have to run the CK classification due to the ash from what oil gets by the rings and gets burned in the combustion cycle. The older high zinc and calcium additives cause problems in the current diesel emissions system, but you have to understand, these newer diesel engines are engineered for these oils. They are all running roller cam followers & roller tappets with less friction than my older flat tappet & cam follower cummins. I’m so thankful that Amsoil still offers the 15w-40 HD Diesel & Marine oil.Bottom LineYes, I would recommend this to a friend.Was this review helpful?
-
star rating
WalterBy YAREMCHUK, a Verified Buyer on August 01, 2025Very good qualityBottom LineYes, I would recommend this to a friend.Was this review helpful?
-
star rating
Great Motor Oil.By ALVIN, a Verified Buyer from 80421 on July 05, 2025I have used this motor oil in a 2001 Ford F250. I have pulled a 38 foot fifth wheel among other things and it has never used a drop of oil. I change it once a year and I have been very impressed with the results.Bottom LineYes, I would recommend this to a friend.Was this review helpful?
-
star rating
best oil I ever ran in a motor,By GEORGE, a Verified Buyer on June 25, 2025great service and great product. don't use anything but amsoilBottom LineYes, I would recommend this to a friend.Was this review helpful?
-
star rating
WalterBy YAREMCHUK, a Verified Buyer from Orland Park,IL on April 14, 2025Good quality,recommendedBottom LineYes, I would recommend this to a friend.Was this review helpful?
-
star rating
amazing qualityBy ERIC, a Verified Buyer on February 11, 2025i did a full fluid flush being , front diff , engine oil , transmission, t case , rear diff . the fluid quality is out standing as for the truck now runs and rolls like new and much more quiet as before. it’s clearly more happy that it was now that all fluids are done. the g56 manual trans shifts like new now and it’s got 140k on it . highly highly recommend AMS oil. i need to do a coolant flush next so if they sell coolant i will be buying it soon. 10/10 starsBottom LineYes, I would recommend this to a friend.Was this review helpful?
-
star rating
