[navylife59]

All true. You want to change out as much of the fluid as possible, but you will never get all of it. Particular contaminants in hydraulic fluid tend to settle in low points (the rack and pinion) and points of slow flow. Ever drain your oil and notice that after the draing oil flow slows down to a trickle, the oil becomes thicker with more sludge? This is why you want to run your power steering thru the paces (lock to lock) with the motor running before you drain (not while you drain). This puts the particulate more into suspension in the fluid allowing more of it to be removed.

As for entering air into the system, yes you will. Once you begin refilling, fill to about 3/4 the amount then slowly move the wheel from lock to lock 10 times. Now top-off to the "Cold" fill line. Slowly move the wheel again from lock to lock for 5-10 more times. You should feel a difference while you are doing this as you are filling the rack and purging the air. Check the fluid level "Cold" one more time. Now start the engine and slowly run the wheel lock to lock till it feels firm. Be sure to kep checking your fluid level while you do this. 5-10 turns from lock to lock should suffice. The pwr steering pump has a pressure switch, so if have too much air trapped in the system, you might throw a MIL (CEL). Once the engine is turning the pump, any air still in the system will become entrapped in the fluid. This will travel up to the reservoir which is not pressurized (Open). This may cause the fluid to "burb" and spill fluid out of the opening so keep the cap on as it is vented. Just put a shop rag over it. Hydraulic fluid is very bad for paint.