What antifreeze/coolant?

Hey, a friend of mine in Bulgaria is getting himself a WRX, and is wondering what antifreeze should he use? I am no good with those, but he said he saw two cars, one had blue coolant and the other one red?

Whats the process with these?

tell him to join here, they will have all the answers for him:

https://www.subaruclubbg.com/forum/

imo any modern coolant with aluminium corrosion inhibitors will do.
basically any coolant that meets the OEM specs of modern manufacturers with aluminium components in the cooling system.
the OE subaru coolant is same as any other manufacturer but apparently has an additive ( headgasket fix).
i know slatterys subaru in Tipperary are using the renault or peugeot sh*t.
obviously the want to flush out what they already have and not mix it.