Originally posted by inspyral
You can always put it in with the engine running. Just let the engine suck some thru a vac hose.
That seems to be the best way to clean the valves up, but if you want the stuff to get down into your rings you have to put it directly into the combustion chamber and let it sit for a while. As long as you know how many cc your combustion chambers are you will be fine if you keep the amount of cleaner under one third of that volume per cylinder.