Pentosin flush necessary?

[loren01@ix.netcom.com (Scott Bermes)]

While checking my fluids to determine if my brake light coming on was 
my bomb or low fluid, I noticed my Pentosin was ok but it was black.  I 
had my two year flush recently of my brake fluid, does the power 
steering fluid be flushed?  If so, how often?  

TIA,

Scott
89 200tqw