Power steering fluid is often one of the more overlooked fluids in a vehicle. Everyone knows they need to change their oil. They even know to add more wiper-fluid. Of course, everyone knows about gasoline and how to replace that. However, for whatever reason, power steering fluid tends to be the forgotten component of vehicle maintenance.
The reality is, there's no real definitive answer and even the car manufacturers vary in their opinions.
The best advice that could possibly be given would be to meet somewhere in the middle. Either every two years or every seventy-five thousand miles, you should change your power steering fluid out.
Changing out your power steering fluid is incredibly important because of how the power steering pumps function. Power steering pumps are hydraulic pumps which put out upwards of sixteen-hundred pounds of pressure. Over years of use, the power steering fluid gets dirty along the way. Dirty fluids create vastly more friction, becoming abrasive. Dirty fluids can even go so far as to ruin the seals in the pump, or the seals on the rack, which can be incredibly expensive to replace.