Best oil i've used in my old 2011 dodgeram 2500 6.7 cummins and i can run for 30000km per changes with the 15w40 400000km on her and still running deluxe!!!
If you love your vehicle and want it to last, then use nothing but Amsoil Signature Series. Best oil you can buy in today’s market, nothing beats AMSOIL. Nothing!
I use this oil in a compact tractor with a turbo-diesel that works hard. The engine starts and stops smoother, runs smoothly, and I am confident knowing the level of engineering and chemistry that went into the Amsoil product that it will help me tractor engine be productive for a long time.
Bottom Line
Yes, I would recommend this to a friend.
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5 star rating
Great product at a good price
By 
Eddie, 
a 
Verified Buyer 
on 
September 02, 2025
I love your motor oil. I've used it in my Cummins for at least 12 years & I have had great luck with it so far! I change my oil once a year or every 10,000 miles.
Best oil on the market exelent quality package for the product and always quick shipping time noticeable difference on mpg and response from beginning to end of oil life
By 
BENNY, 
a 
Verified Buyer 
on 
August 25, 2025
Seems like a good oil, truck seems to like it! It arrived pretty quick too. What’s odd is after changing the oil to this oil (previously had valvoline blue 15w40, for the Cummins) I started to smell fresh oil out of the vents at stop lights/idling. I replaced a broken crankcase breather tube figuring that was the issue. Didn’t fix it and after some reading apparently that’s a pretty common thing with 3rd gen dodges and with certain oils. Odd. But the truck likes it and it stayed clean on the dipstick for a while after changing the oil.
Bottom Line
Yes, I would recommend this to a friend.
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5 star rating
Great product
By 
PAUL, 
a 
Verified Buyer 
on 
August 17, 2025
If you’re working your truck, you should be using this oil, nothing less.
By 
JEREMY, 
a 
Verified Buyer 
from 
Space Coast Florida  
on 
August 08, 2025
Love it! The engine is quieter, the dip stick is cleaner and I know she’s running with the least resistance possible!
Bottom Line
Yes, I would recommend this to a friend.
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5 star rating
Huge improvement in performance r
By 
CHRIS L, 
a 
Verified Buyer 
from 
Sonoita Arizona  
on 
August 07, 2025
Started using the AMSOIL Signature Series 15W-40 100% Synthetic Max-Duty Diesel Oil in my 2021 Gmc 3500 HD. I immediately noticed the engine running smoother and quieter. I've noticed less DPF regens, fuel mileage improment (from 568 miles a tank to 612 miles) a little power increase and engine oil temps around 8-10°F cooler. Very happy with the switch and definitely worth the extra $ for a superior product.
Pretty much the same price as the other Diesel oils, but way better! If you watch them test Amsoil versus other oils on Youtube, you will see the proof in the Cold oil test, hot oil test, and bearing test, that's all you need to see to know that Amsoil is one of the best oils in the world!
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