Lightning McQueen originally promotes Rust-eze in Pixar's Cars.
Rust-eze is a fictional automotive product marketed as a rusty-bumper ointment. McQueen begins the film in Rust-eze's red-and-yellow colors while trying to win the Piston Cup and secure a more prestigious sponsorship from Dinoco.
The sponsor is central to McQueen's early characterization. He initially treats Rust-eze as an embarrassing stepping stone and focuses on his own fame. His time in Radiator Springs changes that attitude, and the Rust-eze owners, Rusty and Dusty Rust-eze, become important supporters of his racing career.
Dinoco is the main sponsor McQueen wants, so it is the most likely alternative answer. However, Dinoco is not his original sponsor in the first Cars film. Rust-eze continues to appear in the franchise, while McQueen's later association with Cruz Ramirez develops through the events of Cars 3.