O'Reilly Auto Parts in Alton is known for great customer service and helpfulness. Customers find the staff to be knowledgeable, efficient, thorough, and always willing to help, even when a customer's own idea isn't quite right. They are praised for selling the correct part needed without attempting to upsell. The store's free Loaner Tool program is highlighted as awesome and invaluable for emergency repairs, with the service sometimes leading to additional tool sales. The team provides amazing support, such as printing and explaining diagnostic codes and assisting with installations. Services include free battery testing, wiper blade and bulb installation, fluid recycling, Check Engine light testing, and brake rotor resurfacing. Overall, customers love O'Reilly, describing the store as great and the parts professionals as always there to help with any project.