POR 15 or Rust Bullet Which to use?

[emmett]

I have not painted my frame yet but I am going POR-15
I used to do maint. on the semis at work before I became dissabled, we shiped roof truses on roller trailers these trailers had a simple air brake system on the rollers consisting of a air chamber diaphram and piston air is applied to diaphram pushing piston out, anyway when these trailers were about one year old when the breaks started going bad there were about 20 of these brakes I started taking them apart the air chamber was packed with rust I cleaned them up and the GM had delt with POR-15 before and gave me a couple pints of it and told me to try coating the inside of chamber I did and 4 years later they still were working good when I changed diaphrams they were were clean no rust inside at all I think this proves POR-15 realy workes and I don't have a lot of money eather, but the time and money invested into my truck if it cost me a little more to protect the bottom I am going with what I know works (JUST MY OPINION )
Thanks for listening EMMETT (lol)