Brett,

I've used both Rust Mort {i.e. Rust death) and Restoleum Rust Converter for years with not issues. There is also one called "Extend" - which cannot be found here - which you could use.
 
I always remove paint and take the metal back as far as I dare before applying it  - The obvious exception here being the seams on the Vanagon ... here, after cleaning out the seam, I simply injected it using a syringe.  

On 13-Sep-2014, at 10:49, Brett Ne wrote:

> So while running errands yesterday I stopped at the hardware store to look
> for rust converter.  They had two different brands of brush on converter.
> They both seem to work the same by converting the iron oxide into iron
> phosphate, a relatively inert chemical.  One container specifically stated
> that it was not recommended for exterior automotive sheet metal.  They both
> stated that it can cause rust if applied to non rusted metal.  Is this
> really a good idea to use?  Does anyone have experience with using rust
> converter and not using rust converter on seams for a comparison?
> 
> 
> 
> --
> Brett in Portland, OR
> "Albert" '82 VanaFox I4 Riviera