People have not known this fact yet but it is a big factor for car owners when they wash their cars immediately when coming back from travel. A friend of mine complained of always changing his brake disc constantly or treating it because of rust or bending, anytime he tries to apply brakes on a high way the car vibrates rapidly and makes a rubbing metal sound. This could lead to brake failure or brake ceasing and can cause serious accident.

Considering the effects of water on a hot metal, take for example you pour water in a very hot empty pot on your stove and If the temperature is high enough, you will see that the water drops will dance around the surface for some time before they disappear or consider a kerosene stove you always quench the fire with water all the time, this phenomenon is called Leidenfrost Effect.

The reason is called the Leidenfrost Effect: When the water touches the pan, a small layer of vapor forms around it. This vapor layer isolates the droplet from the hot surface and protects it from evaporation. And this effect causes rust of any metal it comes in contact with.

Please Note: Do not keep washing your cars immediately after driving a long distance or when your car is very hot because it can cause rusting of any component made of metal in your car, allow you car too cool first before washing it.
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In few years time I will come back and read this

Very informative op.