One of the things every farmer and handy man needs to have around is WD 40. This humble spray is available at some stores for only a few dollars and, yet it can save the day, getting hard-to-turn nuts off, and driving out water. It is one of the world's biggest trade secrets, and there is no patent for the product. A patent would only have lasted a few years, then anyone could make it. But the manufacturer gambled on no-one being able to replicate the formula, and they were right, although there are other, somewhat inferior water repellent products.
Back in 1953, some engineers formed a company called Rocket Chemical Company, and created WD-40 to be used in the aerospace industry as an anti-corrosion agent. The product worked so well that the company eventually marketed it for the public. They also figured that they had so much difficulty creating the chemical, that it would not be easy to reverse-engineer it, so they did not go the patent road. And to this day, the secret recipe has not been discovered.