I use whatever brand Power Steering fluid that I find at the auto parts house. It's not like engine oil where you have to worry about additives or weights clashing from one brand to the next.
The method I use for flushing/changing the p/s fluid is actually a question on the ASE test. Remove the return line from the reservoir and lower it into a drain pan. Remove the reservoir cover. Stand above the reservoir at the ready with two quarts of p/s fluid. Have an assistant start the engine and start turning the steering wheel back and forth, lock to lock. After the reservoir empties, start pouring in p/s fluid until the two quarts are gone and flushed through the system, then tell the assistant to shut it off.
Reconnect the return line and fill the reservoir. Have assistant restart engine and start turning lock to lock to bleed system as you carefully top off the reservoir.
Engine oil of ANY kind is a BAD choice for your p/s system. It has detergents that will create foam. The main characteristic of p/s fluid vs. engine oil is that it does not tend to foam.
Have a great day,