About 80 percent of Americans use WD-40 [source: Watson]. The spray, which comes in a familiar blue-and-yellow can with a narrow, red straw stuck into its nozzle for dispensing, was originally developed in 1953 to prevent corrosion. The chemist who invented it sold the formula -- which he'd kept secret -- and his company for $10,000 just a few years later.
Today, WD-40 is used for everything from removing sap, tar and adhesives from various surfaces to cleaning tools and equipment. It's the company's only product, and its secret formula was never patented so competitors could never discover what's in it. The company does reveal what's not in WD-40: "silicone, kerosene, water, wax, graphite, chlorofluorocarbons (CFCs) or any known cancer-causing agents" [source: WD-40].
The revered formula has been sitting in a bank vault for years; it was taken out once when the company changed banks, and again when the company's CEO, armored and riding a horse, brought it out for the company's 50th birthday [source: The Wall Street Journal]. To further protect the formula's secrecy, the company mixes the substance in three different cities around the globe, then passes it on to its manufacturing partners [source: Daily Finance].
In reality, says Cabrini College Assistant Professor of Business Scott Testa,scientists have figured out, for the most part, what's in WD-40. "But some trade secrets are kept secret because from a marketing perspective, there's a certain allure if something's secret," he says. "This is probably more of a marketing exercise than what I'd consider a scientific exercise."