In the US, a filling station that also offers services such as oil changes and mechanical repairs to automobiles is called a service station. Until the 1970s the vast majority of gas stations were service stations. These stations typically offered free air for inflating tires, as compressed air was already on hand to operate the repair garage's pneumatic tools. While a few filling stations with a service station remain, many in the 1980s and 1990s were converted to convenience stores while still selling fuel, while others continued to offer services but discontinued offering fuel.