I have a 1998 Buick Skylark and the fuel tank is leaking; therefore, I purchased a new Spectra steel tank. I am sure the gauge is far less then the General Motors version. I would like to protect it as much as possible from rust, being that I live in Northeast Ohio. I have some POR 15 and 3m Rubberized Undercoating that I was thinking of using. What do you recommend and what process do you recommend?