rusty bottom...

[guruerror]

Originally Posted by Bimmer9938

What you did was just cover up the rust, it will continue to spread under the under coating. You need POR 30 paint, it converts the rust to a paint. I've been slowly doing sections as needed. It's expensive, but it's final. It dries shiny but unless you spray a UV protectant on it will fade to flat black which matches the factory undercoating nearly perfect. Wear gloves cause nothing takes it off your hand, it will be on for your hands for days otherwise.

http://www.por15.com/POR-15/productinfo/1GB/

Interesting...

I've been using Duplicolor Rust Fix followed by their Aerosol Bed Armor. Their 'Bed Armor' product is a slightly rubberized version of spray on liner. It's not quite as gummy as the straight-up undercoating...the combo seems to work well and may not be as expensive as some other proposed solutions.