I'm wondering this same question. I just replaced my battery from VW dealership with the part number 000915105DH for $132. It talks about a degassing plug on the literature but is really terrible instructions. Just like Big Chris, I have a clear plastic plug by the positive terminal. Do I have to try and pry out this white plug and put the red plug that comes with it or just leave the white plug in there?
I have been reading everywhere and cant find anything about it.
Thanks,