Customer Ratings & Reviews

I'm taking their word that it works but really don't have a clue if it really does anything or not.

Not sure if this is a high octane product, the car feels faster when used, and back to normal after a tank of gas. Feels the engine is running smoother.

I have been using Upper Cylinder Lubricant for two GM 2.4L GDI Engines with great results. One engine is approaching 120K miles, the other 100K miles. Neither has had issues with injectors or carbon deposits that typically build up on pistons and affect low tension piston rings.

I love all Amsoil products, they're high quality products, I've been using for 20 years now, my cars are lasting forever. Thank you Amsoil.

I started using this on my new 2021 Gladiator once per month but couldn’t really notice anything. After about a year, I upped my usage to every fill up. Still didn’t notice much of anything. Discussed with my gearhead mechanic buddy and he said it was probably overkill but couldn’t hurt as long as I wasn’t using low quality gas. So I stopped using it for some months and that is when I noticed that the engine just seemed to run rougher or not as smoothly. I decided to restart using the stuff and almost immediately noticed the smoothness return. It’s definitely doing something and I’m not having to skip meals to pay for it so I will continue to use it at every fill up.

We like the product and use it at every fill-up. The one downside is the foil seal is hard to remove, with no pull tab.

I have been using this gas additive every fill-up in my Jeep since it was brand new, and I put a bottle of the P.i. Performance Improver Gasoline Additive in every oil change. Amsoil has never let me down. I'm a firm believer in all their products.

Love this product works great in my vehicle.

If you have a direct inject engine, this is a must to have any hope on keeping it running smoothly. It simply works, what else need I say!

My car already runs quiet and smoothly , but since I've been adding this product at each fill up , somehow it made my engine even quieter. I think it's doing what it says it will do , and quieter means less friction , so I'd definitely recommend it. You really can't go wrong using Amsoil products , and I've only had great experiences.

Makes the idle smooth and lubricates good

As advertised great product.

Great service

Impressed with the quality

I run this in my Gravely mower, Honda 420 and Polairs 1000 after every oil change along with 90 octane non ethanol. Never have had any problems

Use in every tank full in 2004 F250 v10 , seems to be cost effective , most of my use is short trips 8 miles average each day so don't expect better than 10 mpg from the V10

I use it on every 3 car fills.

I have been using this product in my Jeep for over two years. I can’t see inside my motor to see if there are any changes but when I add to a tank of gas I notice the engine runs a bit smoother and quieter. That is evidence to me it is doing something for my engine. It is relatively inexpensive insurance.

Great use it in all my vehicles. Good stuff use it it my four-wheelers & lawn mower as well

I’m not sure how a consumer like me can accurately review a product with proof without proper testing labs, controls etc., that would require long-term observation and internal inspection of engine components affected. So, I’ll just share the knows. I’ve used this product in my 08 Sierra since it has had 7 miles new and no issues, complaints or problems and I continue to use it every oil change. That’s about all I can say concretely. There’s definitely no harm using it.