Por15 is only good for surface rust on strong metal. The soft spots will still have to be cut and replaced by metal.
That's true. Use good judgment when using it. If the metal is so eaten up with rust that it won't support the weight it was intentionally intended to support, then replace it with new metal. My trunk was suffering from a small amount of surface rust, so I used a product from Ace hardware called "rust away." I used it about 3 years ago and painted it black. Well, today, I went out and raised the mat in the trunk, and the trunk area to include the top of the gas tank is still black with zero rust. I think that bottle of "rust away" cost me maybe 7 bux. Works great.
