Rust-eze made the medicated bumper ointment advertised in Pixar's Cars.
Rust-eze is a fictional automotive product and sponsor in the Cars universe. Its advertising features rusty vehicles claiming that the ointment can improve their appearance. Lightning McQueen initially dislikes being associated with the brand, but his sponsorship becomes important after the events surrounding the Piston Cup race.
The Rust-eze name is also part of McQueen's racing identity. Rust-eze sponsors him in the first film, and the company remains closely tied to his career throughout the franchise. The product's joke depends on treating automotive rust as an equivalent of a human cosmetic concern.
Rust-eze is often confused with Dinoco, another major fictional brand. Dinoco is a fuel and racing sponsor associated with The King and later McQueen, while Rust-eze is the bumper-ointment company. Neither name is the championship itself: that competition is called the Piston Cup.