Dura Lube HL-DLFS-06 Advanced Fuel System Treatment, 16-Ounce, Single Directions: Add full contents of Dura Lube fuel system treatment to gas tank at least every 3,000 miles; treats up to 20 gallons of gasoline Helps maintain intake valve and port cleanliness Restores injector flow, attacks carbon build-up and deposits Helps remove intake and exhaust stem gum Works in gas only