Jett here. Every garage in America has at least one dented old can of WD-40 sitting on a shelf, right? It's usually next to some rusty screwdriver, a mystery screw, and a suspicious roll of duct tape that’s been there since the Clinton administration. But here’s the wild part: almost nobody on earth knows what’s actually inside the can of WD-40. Why? Let’s get into it.

WD-40 is household magic in a blue-and-yellow can.

Squeaky hinge? WD-40!!

Rusted bolt? WD-40!!

Do you have a stuck zipper, some weird mystery grime, a stiff bike chain, or a haunted, creaky garage noise? Don't sweat it guys, your neighbor's already walking toward the shed yelling, “Hold on, I’ve got something for that.”

WD-40 is a can filled with miracle juice. But the real magic is that more than 70 years later, the company's still kept the full formula locked away like it’s a nuclear launch code.

And no, I'm not kidding. It's one of the most guarded formulas in the world.

The full handwritten recipe is reportedly stored in a concealed Bank of America vault in San Diego. Getting into the tiny club of people who’ve seen it requires nondisclosure agreements, a special key controlled by the company’s top lawyer, and CIA-level secrecy.

Even CEO Steve Brass, who’s been with WD-40 for more than 30 years, only got to see the formula about 18 months ago. He said it was like getting into Fort Knox.

Am I about to reveal the secret formula to you? Hell no, but I am going to share some really cool Americana lore that you probably didn't know about.

SOURCE

Membership in one of San Diego's most private clubs comes with no bar, no food, and one perk: a glimpse of the recipe for WD-40. Only a handful of people worldwide have seen the full, handwritten formula for the 70-year-old lubricant, which is used for everything from loosening rusted bolts to getting gum off of turtle shells. As the Wall Street Journal reports, entry to that inner circle requires nondisclosure agreements, a special key controlled by the firm's top lawyer, and a visit to a concealed Bank of America vault where the notebook with the recipe is stored. CEO Steve Brass, who joined WD-40 more than 30 years ago, was allowed in only about 18 months ago. "It was like getting into Fort Knox," he says.

The notebook itself contains the successful "40th" water-displacement formula, as well as the 39 failed tries that came before it, plus at least one plain warning—"Do not smoke," recalls finance chief Sara Hyzer, who viewed it alongside Brass. Even senior scientists are kept out. Meghan Lieb, who's been at the company for two decades and is now head of R&D, still has never seen the formula and works from a coded version instead. She says her own family likely assumes that she must know what's in it, but she swears she doesn't. Hopefully no one takes a giant eraser to the notebook, either, as the Times of London noted a few years back that the recipe is scrawled in pencil.

Outside the vault, speculation is constant. Online forums debate ingredients—fish oil, citrus, coconut, vanilla?—with WD-40 officials knocking down the more popular myths. A past lab analysis by Wired captured some broad components, a company spokeswoman said, but not enough detail to actually reproduce the product, which still accounts for nearly 80% of WD-40's revenue. Reddit users now focus less on what's in the can than on what to do with it, trading thousands of ideas that range from detangling horse hair to killing wasps. As for expanding the secret club, Brass says he may add a few long-serving employees if the company ever reaches $1 billion in sales—but not, he insists, his own board.