15w40 AME & a 15micron Donaldson P551018 for my annual oil/filter changes. From Southern summers to Northern winters, UOA shows that this combo can't be beaten for my over fueled, compounded decathlete 12v Cummins. Don't ever stop making this outstanding CI4+ oil.

Been using since 2003 in Duramax. Handles all climates.

Switched to amsoil in my 2006 f250 powerstroke. My truck now starts much better, and runs quieter and smoother!

Only oil I've ever used in my 6.7 Cummins for last 100k aside a rotella hear and there. Also use the amsoil oil filter. Works well together !

I've run Amsoil in my 05 Cummins 5.9 for around 200k. And I've used all the different diesel oils Amsoil has to offer from highest of performance to the eco price. But In my leaky 300k plus and climbing work diesel. the marine oil always comes out with just about as much as I put in 10k ago. And the others I would sometimes be up to 3Qt short when drained. Like it's gets so thin that it finds completely new ways to seep out !! But that why I like to order the heavier oil. Lastly my whole truck runs on Amsoil rears,difs,transfer and engine, and I strongly believe that Amsoil is the soul reason why my Cummins runs as good as it does at 310k miles!! Thanks for the spectrum or synthetic lubes to chose from!! Two thumbs high from this guy!!

Amsoil heavy duty 15w-40 marine diesel oil has proven to me that it will protect my Cummins engines. I have older high mileage Dodge trucks that get driven on the highway, gravel roads in -15F cold and 100F heat and the lab results from my oil samples have continually came back great. At a minimum I put double the factory recommended mileage on this oil before changing, depending on driving conditions.

Reduced engine noise (duramax)

I've been using Amsoil diesel and marine for many years I drive 200 miles a day in my Cummins in and out of petroleum refineries 6 to 7 days a week and I work my truck hard! Amsoil has never let me down! This is a great product

I have been using Amsoil in my 2003 Chevy Duramax for its entire life with great results.

This 15w-40 Marine oil is all I use in both my 2001 300hp Mercruiser boat engines since 2011. Why you might ask? 1) Only oil that has shown to lubricate the turbo blades on my son's boat diesel super-charger. 2) When son's oil hose ruptured at full engine speed, repair mechanic stated that engine only survived due to the oil's lubrication properties.

We have been using this product in our 2004.5 Dodge diesel since 2010. The truck had 110K miles on it when we switched over and added the micro-filtration unit. We now have some 329K miles with about 120K miles of that amount while hauling commercial freight. Now back to my daily driver and still using this oil.

Product is great. 8-10,000 miles between oil changes. Price is right. You might as well go with the best.

It helps my 7.3 powerstroke start better since the injectors are oil fired it will start when 0 degrees without being plugged in

Oil is like a lot of things where the positive traits are hard to quantify. You just have to know it's good and working. I run it in a Ford 6.0 so it has to be good.

I'VE BEEN USING AMSOIL SINCE 2004 AND I JUST LOVE THESE PRODUCTS. IN MY OPINION AMSOIL IS THE BEST OIL OUT THERE NOTHING COMES EVEN CLOSE. I HAVE A 2002 TOYOTA SIENNA WITH 570.000 MILES YES YOU SAW IT RIGHT 570K MILES AND THAT THING JUST KEEPS ON GOING AND GOING, IT JUST DOESN'T WANT TO QUIT. STILL ORIGINAL ENGINE AND TRANSMISSION. PEOPLE TOLD ME TO GET RID OF IT BUT I TELL THEM IT'S NOT THE TIME YET IT STILL RUNS LIKE A CHAMP AND EVERYTHING IS WORKING ON IT. I USE AMSOIL PRODUCTS ON MY OTHER CARS AS WELL AND A FEW OF MY FRIENDS GOT HOOKED ONCE THEY TRY IT AND THEY NEVER WENT BACK TO THE OIL THEY USED TO USE. THANK YOU AMSOIL FOR YOUR GREAT PRODUCT, KEEP UP THIS AWESOME WORK AND I WISH THAT AMSOIL TO BE AROUND FOR THE NEXT 100 YEARS. BEST WISHES AND GOD BLESS AMSOIL!!!! ISTVAN.

All we use in all our truck&tractor,

I have been using this oil sense I bought my 07 Dodge Ram diesel new 12 years ago. I go 15k between oil changes. I'm glad I started using this Oil and the by-pass system when I did. I have 250k on my truck now and plan to go another 250k. Amsoil has been great every time I place an order as well.

Have been using heavy duty diesel marine synthetic motor oil in my duramax work truck for last 70,000 miles. Seems to have superior protection and less breakdown under heavy loads and extreme conditions.

Motor oil

I run this oil all winter long,every winter