I have a GMC truck with a Vortec engine that is known for having clogged injectors. I had used several different cleaners before I tried your product. When I added your fuel treatment, the results were almost immediate. I began adding it at every fill-up to keep from having injector problems, and it was very effective. I recently pulled the engine to replace a leaking intake manifold gasket and other leaking seals. To my total amazement, when I pulled the intake manifold and took a look at the intake passages and valves, there was NOTHING! Not a speck of varnish or carbon on the valves or passages. Just gray metal intake valves and shiny aluminum on the manifold! The valves looked like NEW! I'd never seen clean intake valves on any engine with 170000 miles before. I'm sold. I'll keep using this product in all my vehicles.