You might want to go to a vw dealer and order the 2 gaskets that go to the
expansion tanks.About $5 for 2(1 or 2 days to order). Dont think you can
get these from a vendor.I hear that sand is kicked up by the tires and goes
into the expansion tanks via bad gaskets  , and then down to the gas tank
and into your fuel filter. I think this can cause premature fuel filter
plug up and fuel pump noise.