I have used this oil for many, many years in my 1985 Mercedes Benz 300SD Turbo Diesel and my 1951 John Deere Model R diesel tractor engine with excellent results. Zero failures

This is the best oil for my 2004 John Deere X495 diesel tractor, the pony motor on my 1951 John Deere Model R diesel tractor and all my smaller 4 cycle gasoline engines. Been using it in these applications for years and years with excellent results and zero engine failures.

This oil seems to break down at approximately 125 hours. The oil turned black and got really thin. This caused my oil pressure to drop 7-10 lbs. I’m going to give it one more try before I witch brands. This oil is being used in a Cummins 5.9QSB that is in my boat and they recommend 250 hour oil changes. This oil will never make it that long. Thank you for your time.

I have used amsoil in my 5.9 cummins for 11 years now. 230k miles and performs like it is new.

Run this in my 2007 pre-DEF engine since new. First ran for 15K and then tested results with SOAP analysis—results were excellent. Now run the oil at least 30K miles, changing filters every 15K. Good MPG and cold wx starts to 0 degrees F. Highly recommend for towing and tough engine use conditions.

I've been using this oil nearly exclusively for the past 15 years in my 2006 Duramax. I average 35,000 miles between oil changes and monitor every 10-12k miles when I change the filters. Amsoil has always provided great protection for my engine. The high TBN lets me use the oil longer than any conventional oil and my truck is running great with 256,000+ miles. Great oil, I'll continue to use it.

This is all I have used in my 97 Ford F-350 Powerstroke. Formulated especially for these motors.

I’ve been using this oil for 15 years with excellent results. High TBN promotes its use for extended oil change intervals. I’ve run several 40,000 mi intervals. Just added the PPE oil pan and filter adding an extra 2qt capacity to the engine, and draining 99% of the old oil. Hoping to get 50,000 mi on this oil!

Have been using this oil since the engine was broken in, now have 276,000 miles on it and still going strong.

I've been using the 15-40 Heavy-Duty Diesel and Marine oil in my 2006 GMC 2500 HD Duramax LBZ since I bought it new and now have 287,00 miles on it and many of those miles towing heavy loads in the heat.

I used this in my marine diesel engine. I had some reservations based on past experience with synthetic diesel oil from another manufacturer (noisy operation), but this far exceeded my expectations. Since switching from the industry standard mineral based oil to Amsoil Heavy Duty and Marine Diesel Oil, I have higher oil pressure and cooler operating temps, and the noise level seems lower as well. I am very satisfied.

Folks, I switched to Amsoil at 150,000 miles now I have 400,000 miles on my truck. I believe the quality of Amsoil and there filters are keeping the engine wear down. My last Blackstone oil sample (paraphrasing here) recommended I increase oil change intervals if desired because the sample indicates an engine of around 130,000 miles. I especially enjoy the the super quick delivery to my doorstep.

I changed the oil in my 2010 F 150 to Amsoil and the gas millage has increased by by 4 miles to the gal. I am very happy with the new oil and will keep a eye on the millage to see if it stays good

i use this oil in my 8030 allis-chalmers tractor. this synthetic oil is excellent we get to 20 below zero here in the winter and i use this tractor on the snowblower and the minute the tractor makes one revolution with the starter the oil pressure light is off and it starts way easier with this oil. i am very satisfied with this product. would recommend to anybody who would want to use it. super product.

This is probably the best in the world.

I work my Diesel hard towing doubles in the mountains you can always count on Amsoil to protect your engine

Have used this product since 1997, and still impress with it. Do oil change once a year (approx 25000 kilometers per yr) send an oil sample to Lab and return are excellent. Highly recommended

I have been using this engine oil in my Diesel Pusher Motor coach for 10 years and would not use another oil. I also have the Turbo Drive automatic oil in Allison Transmission and because this transmission is not only very good but it is an expensive one that I only want the best oil in it. I actually replaced the recommended Castrol Transynd oil that was in it to this Amsoil one and noticed that the shifting is smoother and the temperatures are lower during use. I monitor all the engine and transmission activity thru a computer while driving so I actually am seeing what is happening at any time, so, these issues I see and not only feel.

I have been running this oil for 15 years in my 2005 superduty 6.0 diesel. This truck pulls a 16,000 lb fifthwheel many miles a year. Engine does not use any oil, have not had any injector sticking, and no turbo coking. Great customer service and lighting fast shipping.