Hi so I’ve owned my mk1 fabia vrs for about a couple months now one of the things I’ve noticed with it is after driving it hard the coolant will turn a really dark colour almost black like but as the car settles it goes back to the original colour now the thing is, I’m not suffering any coolant loss, no overflow, no coolant boiling, no sign of oil in the coolant, I’m sure it won’t be a head gasket the car runs mint and have no issues what so ever no unusual smoke from the exhaust..

I just wanna try and figure out why is it black after booting it!!? 

Another thing as well to mention is once turned off it’s a matter of minutes where you see the colour starting to lighten up, as far as the coolant it doesn’t look, feel or have the consistency of oil mixed with coolant so I really have no idea why it’s doing what it’s doing, could it be a sign of the radiator starting to need replaced? 🤷‍♂️