this oil by far is the best for my diesel engine. what i do not like is getting weekly, bi-weekly emails with continual free offers from the company when you buy something. it is not like i need to buy oil every few weeks. but i continue to get offers. why not make a list of free offers so when you do buy product and meet a certain dollar value -- you have a list of promotional material to choose from as a free gift from Amsoil. Pick one!!! i would of liked the bottle koozies - which were offered after i placed my order. i did get free shipping which is appreciated, but the continual marketing promotional offers need to be addressed and consolidated. no complaints with the product at all.

The oil holds up in all conditions a good bit more Money but seems to be well worth it in the long run for the engine. 7.3 Ford motor

Been using it for years

Love this stuff for my 6.4 powerstroke. I used T6 previously and I prefer this over it. At the end of 5000 miles, I believe this oil is in better shape. I’ll continue to use this and will be swapping my differentials over to AMSOIL at the next change. Thanks!!

Always a great product

It's real synthetic oil, unlike other brands that are allowed to claim full synthetic while using super filtered black sludge from the ground. The FTC threw it's hands in the air and said: " call it whatever you want to "

Only oil I use in my 2002 7.3 diesel superduty 3/4 truck. 234K miles so far. Love the longer oil change intervals. Hope to keep this truck on the road for many more miles. I have driven it into Canada and all over the Pacific Northwest. A great piece of mind knowing I have the added protection. I can easily recommend this oil for others.

Love this product seems to make engine run quieter. Love that it can be purchased in 10 quart jug.

Best damn oil ever, I not only use this diesel oil I use Amsoil in everything my cars my motorcycles, ATV, generator, transmissions. Literally everything runs stronger and cooler dropped my Harley's running temperature 15-20 degrees!

I use this oi in my 2006 John Deere 3203 compact utility tractor. Besides miscellaneous jobs throughout the year, I brush-hog a couple of acres in the fall. The oil lever never goes down.

I was able to extend my oil changes with Amsoil, and it stays clean longer. My 7.3 powerstroke runs better. I want use anything else.

I use only this oil in my 2018 Duramx.

Awesome oil couldn’t be happier with it

Driving 07 Chevy LBZ run this in the summer for the warm temperatures so far I have not had a problem

I’ve got a rare 2003 F250 with the 7.3 in it, bought it new. I’ve been running AMSOIL Synthetics in it (engine, transmission and differentials) with the dual bypass filter system since approximately 2010. Zero mechanical issues. Sure it may cost a little more however, the protection and piece of mind are worth it! Wouldn’t use anything else.

Heavy Duty 15-40 Amsoil is a great oil for my 7.3 in my 2003 F-350 my engine is protected from normal wear to the engine I cannot say enough to the protection it gives me for my engine! Thank you AMSOIL.

Lasts longer worth the price for the protection and the mileage/hours on my trucks and equipment.

Slowly Switching all my trucks fluids over to Amsoil. Truck seems to run smoother now that I’ve switched the engine oil over.

12 quarts of oil does the job perfect for a 6.7 Cummins for it to go tow 10k no problem.

Anywhere I use oil or fuel treatment I use Amsoil only excellent product