Hi again Burnzie,
Luck is the operative word, well selected!
When an injector requires cleaning, checking for correct spray pattern and precise fuel quantity delivery, there is no additive in the world that can do this.
Injectors must be cleaned in an ultrasonic bath, spray pattern checked then all checked together to confirm that each injector is delivery the same and correct quantity of fuel.
Additive manufactures will tell you anything to sell their products, you pay the money so you make the choice and take the chance.
It is false economy and some cases especially where injection systems are concerned can make make matters worse.
GMSAHFR