My engine currently has pink coolant in it and I can't find any pink coolant anywhere anymore! Is it true that you cannot mix coolants- or am I being over cautious by worrying about it?
As long as the strength of the anti-freeze is high enough for the winter I don't think the colour matters. The colour comes from the dye added to stop people drinking it (by accident or otherwise!). Shouldn't be a problem mixing it. Just check the dilution rate on the bottle.
Use any ethylene glycol-based antifreeze. The pink colour is simply a dye. The concentration to use is usually one part water to one part antifreeze but check to manual first.