There’s a club in San Diego that’s perhaps more exclusive than Soho House and harder to get into than some of the most elite colleges in the country.

It requires a special key, nondisclosure agreements, passage through a bank vault and, typically, an executive title. The drinks don’t flow, members don’t rub elbows with notable people and chefs aren’t filling plates with tasty bites. The only perk is knowing the secrets of the world’s most famous lubricant. And yet, for those in the know, there’s no greater privilege.

“Actually getting in there, it was like getting into Fort Knox, quite frankly,” said Steve Brass, a recent inductee.

Brass is chief executive at WD-40 , the more than 70-year-old company behind the red, blue and yellow cans used for everything from loosening bolts to coaxing a boa constrictor out of a car engine compartment and removing gum from turtle shells. He was admitted around 18 months ago to the small society of people who have seen the product’s secret formula—a feat that came more than three decades after joining the company.

The handwritten formula is kept in a lockbox at an undisclosed Bank of America location in San Diego. It’s only left a bank vault three times in the past 30 years.

There was the time then-top executive Garry Ridge rode into Times Square on the back of a horse wearing a suit of armor with the formula in hand to celebrate the company’s 50th anniversary at Nasdaq. An armored vehicle moved it—or rather moved Ridge, who was handcuffed to a metal briefcase holding the formula—from one bank vault to another in 2018. And most recently, in the summer of 2024, Brass and finance chief Sara Hyzer got a peek while signing paperwork at the bank.

That viewing involved a couple weeks’ notice, several nondisclosure agreements and securing a key held only by the company’s top lawyer. All for a few minutes with a notebook holding the 40th attempt at a formula—and the 39 failed attempts to get it right. (The WD stands for water displacement.)

Neither executive had any idea what they were looking at.

“I’m not a scientist, so I’m not going to recall what was on there,” Hyzer said. “The one thing that was written in the notepad that I do recall was, ‘Do not smoke.’”

Most WD-40 employees have never seen the formula, and never will. This includes the ones who would understand it, like Meghan Lieb, head of research and development. She joined the company as a scientist 20 years ago, thinking she’d get to see the magic behind the lubricant eventually. Those hopes were dashed pretty quickly.

“My family probably assumes I know what’s in it,” Lieb said. “I think they would be like, ‘You’ve been working there a long time. Why don’t they trust you?’”

The notebook in the vault is the only version that has the full makeup of the original formula, which accounted for nearly 80% of WD-40’s revenue as of August 2025. Most company insiders tasked with drumming up new potential uses and products use a coded version to maintain the secrecy.

Lieb has come to peace with her outsider status. The mystique keeps things exciting, and it doesn’t prevent her and colleagues from working with the lubricant. Still, she admits a certain cachet attaches to the few who have seen—or even been near—the notebook.

“I think Wendy’s cool because she saw it,” Lieb said of a colleague who has glimpsed the outside of the formula diary.

Claudia Fenske, who has been with the company since 2012, thinks she knows one person who has seen the formula: an external regulatory consultant who assesses the health and safety of the company’s products.

She speculates that Lieb may one day see it. But WD-40’s head of innovation is less hopeful for herself: “I’ll never know.”

“Of course there’s curiosity, but I think there’s pride and ownership for people to almost keep that secret going as well,” said Fenske.

For outsiders, it’s a different story. Consumers deliberate in chat groups about what’s in the cans. Is there fish oil? (No, according to Lieb.) Some mixture of orange peel, coconut oil and vanilla to create the sweet smell? (Also no, according to the company.)

Wired magazine sent the product for lab testing over a decade ago and came up with a list of components .

The publication got some of the components right, according to a WD-40 spokeswoman. “However, many of the chemicals mentioned in the article are described at a very general level,” she said. “It’s similar to saying you know what’s in Coca-Cola —carbonated water, sugar, and caramel color—yet simply mixing those ingredients together doesn’t come close to recreating the finished product.”

With limited scope for that query, Reddit posters tend to turn to another that seems, in some ways, limitless: How to use the lubricant. The company has sanctioned more than 2,000 possibilities. Reddit users find more: “We used it to help get all the tangled bundles of burs out of our horses’ forelocks,” one user posted. “WD-40 attracts fish,” someone chimed in. “I use it as a bee and wasp killer,” another wrote.

WD-40 tracks their guesses—mainly to correct some of the more popular wrong answers, particularly when they could be unsafe. People in the company, meanwhile, tend to spend their time speculating about who knows the formula, not trying to crack it.

Brass, the CEO, may one day open up the club’s guestlist, perhaps when the company hits $1 billion in revenue. (Revenue was around $620 million in its most recent fiscal year.) But it will remain an exclusive list. Long-tenured employees may make the cut.

“There is no way I’m showing my board members our formula,” he said with a laugh.