Your WALNUT CA OReilly Auto Parts store is one of over 5,000 OReilly Auto Parts stores throughout the U.S. We carry all the parts, tools and accessories you need, as well as offering free Store Services like battery testing, wiper blade & bulb installation, check engine light testing and more. Need help? Stop by and talk to one of our Parts Professionals today. OReilly Auto Parts: Better Parts, Better Prices, Every Day!