dark dark brown coolant

[edprush]

I have been looking for a used vehicle and I've popped the hood on 5 cars/trucks and every single one has very dark (almost black coolant) in the reservoir.

I can't imagine that dark coolant could not be a sign of trouble but each person that is selling the car tells me they haven't had any problems with overheating.

How could a closed system like the coolant system ever get such dark colored antifreeze in it?

Also, coolant doesn't evaporate, right? So if a radiator is a gallon low then it is leaking somewhere right?

 

[bctbct]

rust or Barrs Leak can darken the anti freeze

 

[zixxer]

IMO it's normally caused by using regular water in the system (vs distilled water). Have it flushed and filled with 50/50 distilled and anti freeze.

 

[Sluggo]

Some cars use that oddball orange anti-freeze which does look pretty dark even when its in good shape.