Unscrew outer blue safety lid, puncture foil seal, and screw on the unique, no mess, flexible spout, provided with the bottle of ProTecta Fuel System Treatment. Place pour spout into gasoline tank and pour entire contents into fuel. For best results use when fuel tank indicator is at one quarter (1/4) full. After pouring in contents fill tank to full with gasoline. Do not refuel until the fuel tank indicator is back at one quarter (1/4) full. This allows the contents to work with one tank to fuel. Each twelve (12) ounce bottle will treat 20 gallons of fuel. For optimum results, use every 4000 miles of driving.