The stuff works. I had a Chevy V8 with noisy lifters (I think all Chevy V8's probably end up with noisy lifters) and tried several different products and techniques to resolve it, all with little or no impact. One dose of this stuff and it was silky and quiet. Don't know how it works, but I do know it was much more effective than anything else I'd used to quiet the lifters in my SUV's engine. Good stuff.