metal etching acid

[barbee6043]

working on another project, been using mixture of muratic acid on floor pans, does fair job of neutralizing surface rust, anyone have something ( afforable) better?? years ago when i played with these old cars, i got a DuPont product ( that worked great), but was high 20 years ago, can't afford paint store stuff noew for sure!! this will be driver but like to clean it up best i can.

 

[GaryS]

White vinegar...one part to four parts water for surface rust, then wipe dry.

I use a mixture of vinegar and lemon juice to soak heavier rust.

 

[challengergary]

Ospho is about $30/gallon and it is basically just phosphoric acid. The benefit of using ospho on rusty areas is it actually converts iron oxide (aka rust) to iron phosphate which is inert