There is a wide variety of cooking oils from plant sources such as olive oil, palm oil, soybean oil, canola oil (rapeseed oil), corn oil, peanut oil and other vegetable oils, as well as animal-based oils like butter and lard.
We called a couple of the brake fluid companies and the answer was two to five years is a safe number for an unopened container. Wilwoodâs tech line claims that if the container is sealed, they feel it has an unlimited shelf life, but I would consider five years to be the limit.
Mercedes Benz, for example, recommends a brake flush every two years or 20,000 miles. Toyota says brake flushes never need to be done, while Lexus, which is owned by Toyota and is similarly made, recommends it be performed every three years or 30,000 miles.