...you put the fuel additive in on an empty tank, while at the gas pump, and then fuel up your vehicle. You also want to do this a couple of tanks immediately before an oil change.
The stuff will get by the rings and into the oil a little bit, so you want to change that oil.
Techron is a good all-a-round fuel system cleaner. Sta-Bil is a good all-a-round storage protector.
If you have a clogged injector, or want to really clean up the valves and such, "Sea Foam" is incredibly effective. I have personally witnessed "Sea Foam" clearing multiple vehicle fueling issues.
