I just saw a Sta-Bil commercial on TV for a fuel stabilizer for long term storage. They claim it not only treats the fuel , but also gives off vapors to stop corrosion of the tank above the fuel level. My first thought was if my Porsche has a plastic fuel tank, this is not an issue. Does anyone know with certianty what the fuel tank in a 2010 Cayman is made of?

Composite plastic.