The seafoam has several applications depending on what you want to accomplish. You can just pour it in the tank and it will help. If you have a car that's been sitting or has bad gas in it, you can run it through the throttle body for a REAL deep cleaning. You can also add it to the oil for an engine flush if I'm not mistaken. Seafoam was developed by a guy in his garage. He patented it and there are quite a few companies jockeying to buy the patent on the formula. It is definately the real deal. It tells you on the outside of the can the different ways to apply it and how to do it. It's around $4 for a can of it.