If you must try it, do it before change of oil. Its true that proper cleaning of fuel injectors can restore their like-new performance but they are not very convenient to clean. They are sealed units and cannot be opened for cleaning. Fuel additives do not remove the debris completely from the injectors. In fact they can cause harm to our vehicles if not used in line with the standard operational procedure.
When we pour such compositions to our fuel tank, their first action is to dissolve hydrocarbon scaling from the fuel tank. All the loosen up sediments pollute the strainer attached to the submersed fuel pump and the main fuel filter. Remaining dirt flows inside the engine and so does the gunk cleaned from the injectors. That is the reason, the professional mechanics and auto websites recommend change of engine oil and filters after usage of fuel additives.
Our mechanics and even most of the users know only one method for cleaning fuel injectors that is pouring fuel additive to the tank. Additives only make partial cleaning and have many hazards associated with them. When poured in the tank, they come in contact with many such parts of the fuel system and engine which they are not friendly with.
In the advanced countries injector clogging problem is dealt with ultrasonic cleaning. Ultrasonic cleaning has capability to clean stubborn debris from microscopic grooves, cracks and holes. Since the fuel injector has tiny nozzle which is designed to atomize the fuel, it is almost impossible to clear with any other mean. Only 8% to 10 % clogging in the nozzle can cause an injector to malfunction. Ultrasonic cleaning is internationally accepted most effective process for cleaning fuel injectors. It is cheap and comprehensive solution for the problem.
