When you're topping up or changing the power steering fluid, it's crucial that you understand just how much fluid you really need. For most cars, a 1-quart bottle of power steering fluid should be enough for a simple top-up. However, if you're flushing the entire system dry, you'll need about 2 quarts or more to completely refill the system. You should be able to find the precise amount somewhere in your car's owner's manual. If you're still unsure, all power steering fluid reservoirs should feature some markings on the side to note the fluid volume. Just be wary that hotter/warmer power steering fluids will expand and rise upward. To be on the safe side, you should slowly add power steering fluid into the reservoir in tiny bits until it reaches the MAX (maximum) indicator.