Keeping your engine and its valves free of carbon build up is big part of the engine lasting longer and most importantly running properly. Do yourself a favor and get yourself this product to prevent build up and ensuring your car runs optimally.

Combine with the PI great results

YOUR SHIPPING COST ARE OUTRAGEOUS. PRODUCTS NOT OFFERED IN STORES LIMITED AREAS. I WON'T BE BUYING AGAIN. THANK YOU.

Seeing that every other product has impressed me I am going to assume this is doing its job.

When you can't really "feel" a product making a difference, but the science and concept seem solid, you just have to let it prove out. Well, I have a 2018 Grand Cherokee with 97K on the 5.7 hemi and it has just as much power today as new. No smoke on start. Used UCL since 14K miles (in addition to Signature Series oil) in every tank without exception. I'd have to say it works!

"The difference between Amsoil fuel additive and others ? Amsoil works ! " Great stuff !

Awesome product

Product works very well and as described.

Thought it was best to add this after sitting a while

You can feel the difference . Almost felt like it stalled and had to check my tachometer. Smooth. I bought a case. :)

Keeps my Ford F150 and wifes Toyota camry running great!

Didn’t really notice a huge difference.

Noticed my mileage increased... Very good product but everything Amsoil produces is very good...

This product far outperformed my expectations. I notice a small increase in fuel economy. The biggest difference is the smoothness of the engine. Works great to use this after running a tank with the Amsoil Performance Improver additive.

Since I started using all Amsoil products, my car runs better than new. The Upper Cylinder Lube keeps everything smooth, easy starts, no carbon pinging, etc. I will never NOT use this product.

I use this to maintain injector cleanliness. Better results than any other I've used. I bought 2 cases and add a bottle at every fill up. I usually averaged 25-25.6 MPG driving 33 miles each way to work. Now, I'm getting 26.8-27.3 (depends on which way I go to work. Definitely an improvement.

I combine this with the P. I. Every other oil change keeps everything smooth.

Hard to say if it’s better just yet.

Both of our vehicles run quieter smoother and stronger, after one tankful of gas.

Been Using this stuff for YEARS now. Price Point is Getting up there as with the OIL'S and all. I'll Keep using it till the Price Increases ONE MOR TIME. Then, I'll make the Switch to something else. At this point I can't say I'am getting any Benefits from it other than it just being a GREAT Additive / Detergent / Product.