The pump growls when I turn the wheel. I want to completely change the fluid. Anyone know of a process to completely remove old fluid? Also, is there a Synthetic fluid that has proven to help a growling PS pump?

__________________
1996 E300D
1996 E320 Wagon 4MATIC
2003 Jetta TDI- GLS, 5-spd
1997 Passat TDI
2002 F350 Crew cab 4x4 Powerstroke
Jacobsen HR 15' cut ZTR w/ 80 HP Perkins diesel
Hustler 6' front deck with 28HP Kubota diesel