They have no idea what is in the bottle. As long as you buy it there (save the receipt for eternity) you will have an excuse if your rack goes to the dogs. Make sure the bottle you buy is labeled VW/AUDI with the logos. It's about $25/litre.
What i don't understand is that I ordered the specific fluid stated on the PS fluid container, however it ended up being synth when I received it . . . . even though the container says use mineral oil only . . . .