Hello Normand.  I've had the brake fluid changed every 2 years, as 
per VW's recommendation.  When I did my brakes on our 9 year old Golf 
this summer (it had 200,000 km on the original brakes!!), I extracted 
the piston from the caliper.  There was NO corrosion in the caliper.  
This is owed to clean, uncontaminated fluids.

Hope this helps,
Harry.

> Hi,=0D=0A=0D=0AThe manual of my Jetta 91 and my Westfalia 85, siad the s=
> ame thing:=0D=0Achange each 2 years the brake fluid. Here in Montreal, i=
> t seems that=0D=0Anobody does this, the VW place were both cars are serv=
> iced have never=0D=0Aask me to do this (and they are able to suggest a l=
> ot of fluid=0D=0Areplacing, :-)). I have ask somebody that had keep a Ni=
> ssan near 14=0D=0Ayears and he said to me that he had never replace the =
> brake fluid.=0D=0A=0D=0AWhats wrong, VW or the people here ?=0D=0A=0D=0A=
> =0D=0A=0D=0A=0D=0ANormand Gagnon=0D=0Agagnon.n@interlink.net=0D=0AMontr=E9=
> al, Qu=E9bec=0D=0A514-873-8888 (travail)=0D=0A514-864-2617 (fax au trava=
> il)=0D=0A514-388-6639 (domicile)
> 
> 
> 
Harry Yates, Langley, British Columbia Canada
'90 Syncro Westfalia   WWW - http://www.bcit.bc.ca/~hyates
'87 Golf Diesel        email:  hyates@bcit.bc.ca