just had the valve cover off my Cummins Marine 5.9. pristine at 1000 hours. Amsoil products are the only oils in all my power equipment.

So far so good Time will tell

Been using this oil since first oil change.

The AMSOIL for my diesel is AMAZING. I would never use anything else. Thank You for such a GREAT Product :-) God Bless Bob

Love many different Amsoil products. Diesel engine oil works great in my Tractor

I've been using Amsoil Synthetic Oil for many years and my diesel engines just keeps lasting.

AMSOIL products are always reliable and ship quickly. Packaging is durable and clean. They've even sent me free bottles of firearm cleaner in which worked so well I purchased them on top of my usual oil orders.

Always use this in every diesel rig. Some now as old as 25 yrs. Never an oil problem. On the road at all times and never down due to oil. Don't use this at your own peril. Peace of mind is crucial.

Love this product great price to. Going to switch all my vehicles over to amzoil.

Fast shipping high quality product

Fast shipping great quality!

Fast shipping great product

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!