Years ago my Dad gave me a wok and showed me how to season it, but I'd never really thought about the chemical reaction that happens when we season metal pans until I read Sheryl Canter's blog post about the chemistry of cast iron seasoning:
I’ve read dozens of Web pages on how to season cast iron, and there is no consensus in the advice. Some say vegetable oils leave a sticky surface and to only use lard. Some say animal fat gives a surface that is too soft and to only use vegetable oils. Some say corn oil is the only fat to use, or Crisco, or olive oil. [...]
They are all wrong. It does matter what oil you use, and the oil that gives the best results is not in this list.