What about when user got a second hand car? Not sure what is the condition of the engine and want to clean it a bit without spending extra money doing overhaul. Engine cleaner is a product that has been recommended by nearly all car manufacturers. We are not talking about things like seafoam or voltage stabilizer or grounding cables or camber nut. These are things that car manufacturer does not introduce for a reason. But nearly all car manufacturers does have their own brand of engine cleaner and recommend them as well. If you say, ya they are useless then do you believe in camber nut? Nearly all car manufacturers does not comes with camber nut. It's not due to cost because it is only few ringgit per nut. Also, they will never recommend you do camber nut if you tell them your alignment is off.