I damaged a honda PS rack from non-honda fluid. I was using Amsoil, thinking, "surely this will be ok."
There is a friction member within the rack that slows it down or dampens its movement. This is a spring-loaded slug that rubs against the bottom of the rack. It has a tensioning adjustment. Around 90k I swapped the PS fluid with amsoil. At that time, the steering was heavy, and was stiff, presumably to give it a sport feel. By 115,000, the steering was as loose as a goose, to the point where rough pavement at highway speeds would completely unsettle the steering and the car would wander everywhere. Remember, the steering shaft is a spring as it passes through the torsion valve, and within the tolerance of that spring, without the tensioner in play, the rack is allowed to move until the valve and hydraulics catch it. No good at 60mph cracked pavement. I bought the rack tool and the torque wrench needed to re-tension the rack. No good - there was nothing left to re-tension.
I've had plenty of hondas that stayed with oem compatible fluid at this mileage and more, and never had this happen, so for what it's worth, that's my best guess as to what happened.
-m