Is engine internal cleaner useful? Will it damage the engine?

I want to ask, will rainwater entering the engine hood of the 570S damage the car?

Which type of engine carbon cleaner is recommended for the Phaeton? Thanks.

Dear car enthusiasts, has anyone added a catalytic converter cleaner to the fuel tank of a 2011 manual Touran? After I added this kind of cleaner, it started emitting white smoke and the check engine light came on. Has anyone experienced this situation?

Is the gasoline filter of the Vitara 1.4T external or internal?

Does installing a supercharger on a 2700 engine cause any damage to the car?

I want to know where the internal air intake vent of the 14th Sunshine is located.

Is engine internal cleaner useful? Will it damage the engine?

Has anyone replaced the shock absorber bushings or other bushings on a 2015 Jetta? As for the engine mount rubber, if it's not severely damaged, should I continue using it?

I'm not sure? When the internal circulation light is on, does it mean the internal circulation is off or on?

Hey guys, do I need to add a fuel cleaner to my Subaru? 😊