The power steering fluid reservoir on a 1997 Buick Park Avenue is typically located
under the hood, near the front of the engine. It's usually a clear or translucent plastic reservoir with a dipstick or markings to indicate the fluid level. Look for a cap that says "Power Steering Fluid" or has a steering wheel symbol.
It might be somewhat hidden, so you may need to carefully look around the engine compartment. A picture or diagram of your specific engine bay would be helpful if you're having trouble locating it. You can find such diagrams online by searching for "1997 Buick Park Avenue engine bay diagram".
