This and my decision to switch to Amsoil 5W30 in my 1999 Chevy/5.7L made my engine as quiet as can be. Highly recommended!!

This seems better than other brand. My average mpg was 23.3. it's now 23.6. mpg. To early to tell. But it's never been up to 23.6 mpg

I usually use Performance Improver at every oil change then use upper cylinder lubricant at every fill up thereafter. Bottom line engine runs great and smooth and mpg are better.

Not only does this product Lubricant you upper cylinders, it also increases fuel mileage! My mileage in my 2018 RAM 1500 w/5.7 jumped an average of .5-.8 mpg when using this product! And if it lubricants well enough to increase mileage think about the added longevity it’s adding to you engine as well! Great job Amsoil!

I use every 5,000 miles. Helps keep my old car run like new.