Customer Ratings & Reviews

08 Duramax 250k miles and still going strong. -30 here in winter, starts up with good oil pressure no waiting on the pressure gauge to pick up cold oil.

Only product I use. The BEST! I use it with AMSOIL FF and bypass filters.

Excellent product, my 2005 Cummins runs smoother than it ever has. I feel very confident pulling some of the heavy loads that I do, knowing that this oil will stand up to whatever I can put it through.

I've been using this in my 2004 Dodge Cummins diesel for 12 years and 120,000 miles and it still runs like it was new.

Very pleased with the purchase. Regens intervals have increased by a significant margin, particularly in the city driving.

This is the only oil I have used in my 2008 Chevy 3500 HD truck since the first oil change. At this time it is not a high mileage truck and generally change the oil due to time limitation and not mileage. However when the truck is being used it is under somewhat severe conditions and I trust Amsoil to take care of it. I will not at this time consider any other engine lubricant for this truck.

could not think of a better oil. longevity, performance, and mileage difference is evident. recommend it for all diesel vehicles. No complaints.

I use amsoil in my 07 diesel truck, I have 7,000 miles on the oil change and still clean according to the lab test! I've used amsoil in different motors and I'm a believer, this oil is spectacular from my personal experience.

I have been using AMSOIL Premium 5W-40 Synthetic Diesel Oil for the last five years and I have never had any issues starting when the temperature drops below -30C/-22F. I switched to AMSOIL after my first winter because I was not happy with the cold weather starting performance of other full-synthetic diesel oils.

Have been using this product in my 2011 ford diesel since day one. I put on about 14,000 miles a year and change my oil once a year. I have never had to add oil between oil changes. I'm amazed even at change time the oil is still so clear its hard to read the dip stick. Ive been trying to figure out something to put on the dip stick to see the oil easier.

Amsoil Premium 5W-40 Synthetic Diesel Oil is the best! I have used it on my diesel vehicles for years, and have been quite satisfied with its longevity and performance.

Using the premium synthetic oil in a 03 cummins, instantly noticed the truck idling better. Glad to extend time between oil changes as well.

I've been using AMS 15w-40 and the 25000mile filter for over 170,000 miles and have been completely satisfied.The fact that I don't have to take the time to get an oil change every 3000 to 5000 miles helps a guy like me who's on call 24/7.

I have been using amsoil in my truck form the day I got it about 5 years ago, Chevy silverado 2500hd Duramax and I have to change my injectors out at 169000 miles the inside of my engine was so clean you could have ate off it. I now have 240000 miles on the truck and drive it as a daily driver over a 100 miles a day. And still use amsoil

I use The 15-40W in my 2014 Ram 3500 with a Cummins 6.7 diesel engine. I pull a cargo trailer daily for my construction business and also have a 40 foot 5th wheel trailer that I am on the road with 45 - 60 days a year. I never have to worry if the engine is being well lubricated.

This product ROCKS! Have used it in my diesel truck since my first oil change in 2006. My truck has 170,000 miles and still runs like a top and still pulls my 5th wheel all over the USA. Also use an Amsoil oil filter and together they are the best in my humble opinion.

I began using AMSOIL 15w-40 Synthetic Diesel oil 3 years ago. I can tell a definite difference in the performance of the truck & there has been increased fuel mileage with & without towing my 5th-wheel. I also have extended the interval of oil changes to 15,000 to 18,000 miles. Based on my positive results with this product I also had my transmission fluid changed to Amsoil.

I Can always count on great quality and fast shipments from Amsoil. I have only used there product on my 2007 GMC Diesel truck from the day I purchased it brand new.

Have used AMS Oil for years and it has performed as advertised. Was always a little tough to find a salesperson close to home now it is very simple to order and delivery was fast.

I switched from the standard Rotella 15W-40 about 1.5 years ago to the Amsoil 15W-40, and was the best thing I could have done! Though some of the new diesels are rated for 7500 mile oil changes, when using Rotella I still changed it every 3k miles. With the new emissions on these trucks, the regular oil doesn't last near as long. After only 3k miles, the oil was almost as thin as water, and the lubricity was nearly gone. After switching to Amsoil, I can go the full 7500 miles and then some (with oil analysis), and the oil still feels like new. I have since started using Amsoil to replace all the fluids in my truck.