In the early years of automobiles, drivers used plain water to fill their radiators. While this was okay in an emergency, it was just that water caused metal products to rust. Buick sold this 4-ounce can of Cooling System Rust Preventative to help prevent rust and scale formation by leaving a protective film on the walls of the cooling system, which helped your Buick run longer and cooler temps. The metal can is full of original fluid and is in amazing shape. Some small chips are on the sides of the can, which is typical with this great piece. 20810-ET