Yeah, but i meant if its used in engines that are full of crud, for eg. engines that have done 100,000km without an oil change you run the risk of it dislodging stuff and blocking galleries.
If your engine is not in this condition, why would you even consider using a flush treatment?
It goes back to what Neil said earlier, if you run it in an engine that doesn't have excess buildup, it can still potentially clean the smaller carbon buildup on pistons walls etc, that help with combustion cylinder sealing.