The power steering fluid like the transmission fluid and the coolant is a special VW spec fluid.
Depending on the number of miles on the car, consider doing a power steering fluid change. If the fluid is not still a nice clear green fluid, it is time to change the fluid. It takes about one liter of fluid to change out the fluid.
Never, ever, use anything other than VW brand or European aftermarket brand products (Like Pentosin). Don't ask me how I know.
You can get the correct Pentosin brand fluid from the independents like www.germanautoparts.com