Rustproofing a car that already has big spots

[Mokmo418]

I am in eastern Canada, i have a 2002 Mazda Protege and i have some rusting spots around the back wheels and the back driver-side door. No perforation that i can see. Most of it is just the paint gone, and this will not last another winter under the salt and calcium.

I seems these are the spots that rust first on this car. I also have tiny pit marks around the car and i intend to put something over it either paint or some other product.

I am a student, still have 2 years to go, repairing around the wheel was quickly estimated at 700-800$ last year and that was before i had noticed rust on the inside of the door.

Questions:
-For the rust around the back wheel, if i show up at a garage that does rustproofing, What will they do ? remve all the rusted parts they can and apply their protective stuff over what remains ?

-for the pit marks, that would be a good solution ? Some are on the main body, which is silver and some are on the doorframes, which are black.

Thanks for the help guys.

 

[CurseTheSky]

Unfortunately, by the time you have visible rust on the outside, enough of the metal has usually flaked away to make it very thin and brittle.

If you're handy with a few tools, you may be able to sand it down and cut out the bad spots yourself. If they're small enough, you can fill them in with body filler (bondo), undercoat everything else that's visible, touch up the paint, and call it a day. If you want it to come out looking nice, or if you plan on keeping the car for years to come, I'd get some quotes from shops. You should show them the car and ask them about what they'll do. If there's cutting and welding involved, expect to pay quite a bit. If 9 out of 10 shops mention cutting and welding, and the 10th shop says you can get away with just filler and rust preventer for cheap, walk out.

 

[lurk3r]

^^ what he said, once the rust starts you're pretty much screwed, all the rust proofing stuff is just going to slow the progression. Your best bet is to remove any rust you can find (yes cut out the rusty bits), and patch it with fiberglass patches (bondo).

I've usually followed up the patches with a black ruberized undercoating instead of trying to match the paint, if you do a decent job it dosent look too bad.