So I tried using some gumout multi-system cleaner stuff today just to try it. I couldnt say if it did any kind valve cleaning or anything but once it started smoking out the back end i noticed it was smoking in the engine bay as well. Apparently I have an exhaust leak somewhere and had no idea. Im still trying to pin point it but I never would have know had I not tried using this stuff. Throwing it out there FWIW!