Best oil made, PERIOD. I’ve used it my whole life and it never lets me down. A++

I have used the heavy duty oil from amsoil, which is great protection. Motor was still little noisy, and switched oil to this signature series and made the motor quiet down alot and run smooth. It's a good one to run.

I use to use Rotella T5 10W30 and was getting decent mileage and protection. When Shell couldn't get the additives to make the T5 oil I changed to Amsoil 10W30. Best decision I could have made! The oil gets me about .5 to 1 mpg increase. I love this oil! I'm glad I switched and don't plan on ever going back!

Love this oil.

I just bought a newer diesel 5th wheel hauler to replace our aged 2002 Duramax. The old truck only used Amsoil 15w-40 Marine Diesel Oil. The new truck takes 5w-40 full synthetic or 10w-30. Since the marine grade doesn’t come in 5w-40, I used the signature series. Looking forward to many years with this new truck using Amsoil.

I began using the Signature 5W-40 Synthetic Max-Duty Diesel Oil in my 2024 New Ford F-350 with the new HO Diesel engine this past fall. I manage a large farm in Central KS and work in very extreme conditions. I’ve been more than happy with it’s performance and trust AMSOIL superior products will protect my engine for a long, long time.

Arrived quick. Great customer service.

Can't get any better than Amsoil!!

I have been using AMSOIL for years now and absolutely love it! I use the full synthetic and won't ever switch.

Perfect thank you

I've been using AMSOIL 5W40 Diesel Oil in my John Deere 1025r for more than 10 years. I store the tractor outside under cover without benefit of a block heater. Even on the coldest, below zero mornings, the tractor starts right up with just one cycle of the glow plugs. Year round protection in all temperature extremes is why I've been an AMSOIL fan for more than 25 years.

All Amsoil products are great but especially the quality of their signature line. I own a Ram 3500 (non dually) with the Cummins 6.7L and my engine runs whisper quiet with it. I can always tell quality oil with how long the engine takes to warm up. Not only that but the viscosity lasts longer than other oils. I'm something of a nerd to checking how thin the oil is when it drains and I always feel like I've changed my oil too soon. A great product hands down.

Best oil ever

I loved

With the oil bypass system on my GMC 3500HD, I Change the oil and both filters at 15k miles. The system takes about 14qtrs, and this size jug saves time not having to open 10 individual qtrs.

I have a John Deere 2305 Tractor that I've always just changed the oil using the John Deere brand oil. I believe in the AMS Oil brand as an industry leader and wanted to try AMSOIL Signature Series 5W-30 Synthetic Max-Duty Diesel Oil. I noticed a difference on easier starts and quieter operation at all RPMs. The throttle response improved too. That was my experience.

Been using Amsoil since 2007

The Cummings ISV 5.0 engine is prone to engine problems. I’ve been using this oil and the oil samples I send out always come back with great ratings. They tell me very low ware and all the readings are well below range. I highly recommend this oil.

Expensive oil but good . I run it in my 12 valve Cummins in the wi winters

I have been changing oil on multiple vehicles for over 50 years. After much research I decided to switch to Amsoil starting with my 2025 2500 GMC AT4X Duramax. My first purchase was on line from Amsoil and my second purchase was from a local distributor. Both experiences were flawless and with the online purchase I never left my house and the delivery was quick and on time. I will continue to purchase online as the entire delivery process was as promised. The packaging was as expected. No complaints.