It will not hurt to gently rev the engine. I would not go over about 2000 RPM. You may need to open the throttle a little while adding the chemical to keep the engine running.
Yes, Berryman's is very potent when used in this manner. Yes, some will was past the rings and make it into the oil. It doesn't really hurt the oil, but if you are changing the oil anyway, change it after doing the cleaning.
