G12 does NOT supercede G11 automatically, G11 and G12 MUST NOT be mixed.
This is do to G11 and G12 being chemically incompatible and it may flocculate.
You are however allright to use G12+ or G12++ (which is the only one you can get from VW now) with
either G11 or G12.
So as long as the stuff you buy is G12+ or ++ spec you can use it in your Golf (even more so if you fully change coolant and not just top up).
Personally I only use red anticoolant to G12++ spec as this is way more friendly with your alu cylinder head
