Lucas additives are awesome for covering up problems in cars you trying to sell. It is NOT a permanent solution for problems. As far as cleaning, some shops will do their best to talk you into cleaning engine, fuel system, injectors, but more often than not, it does not improve anything, and in some cases it actually harms your car. Our shop not just does not offer that service, we recommend against it. If your runners, or throttle body is full of dirt, spraying stuff into it wont do much, the dirt will go farther in, those components need to be removed, and cleaned good, with a toothbrush, and in some cases a scraper. gaskets replaced, and idle speed controller/air bypass, is cleaned as as well, dirty lines are disconnected and flushed with solvent and compressed air, Dirt needs to be removed, not pushed farther in, we do not clean injectors, it is a scam, in rare case that they are clogged a lot, they are replaced. but it does not happen often, i'd say it is pretty rare occurrence.