I used to have a car (1989 Opel Vectra) where the coolant was green. However, for my two newer cars (2011 Toyota Yaris, 2016 Toyota RAV4 hybrid) the coolant is pink.
What does the color of the coolant indicate? Is it an inherent property of the chemicals used in the coolant or some coloring added to distinguish between different types of coolant?
Are there other possible colors than green and pink?
If two coolants have the same color, is it enough to indicate compatibility with each other?