What is best type or guage of sheet metal to fix rust holes in body of car ?

I've seen in the local hardware store I think guages like:
.016 (kinda seem very thin and flimsy)
.022 (seemed pretty thick firm and not flexible or cuttable at all)


So what is the best or correct guage used to screw or rivet or weld into a car to patch up rust spots ?

What about Brass ? What is brass made up of? (I forget - tin and copper?). Will brass rust?

Can ya get sheet metal that won't rust? I picked up some sheet metal screws in hardware store. They had two kinds -
regular (will rust) and stainless steel (guess wont rust).
Both cost same.

Why can't I get or use stainless steel sheet metal ?
Is it cost too much?

Any help or advice on sheet metal would be great!

 

Any good info/ideas about my metal questions?

What about use of aluminum on patching rust rot?
At least aluminum is more flexible and won't rust AGAIN!

 

As far as what gauge metal to use, I don't know numbers but most stores that sell autobody repair stuff (eg. Canadian Tire, Part Source) have a rack near that section with pieces that are the appropriate width for what your doing.

I don't know about using stainless (which you are correct, will never rust) or copper, but I know if you do the repair properly, prep and seal the metal, and paint it right, it should never rust. Rust usually starts because of a scratch of crack in the paint allowing water to seep to the bare metal. So if your body is perfect, it's kinda rustproof also. Keep in mind, that the body panels can rust from the inside out though, so both sides have to be sealed up from water some how, or rust will start after a few years.

Problem with using alluminum is that I don't think you can weld alluminum to steel, but I could be wrong. When welding alluminum you need a tig welder.

 

What about cutting out the pieces you need out of another thirdgen floorpan and use those??
That way the dimensions will be correct.

 

Oh yea, in additiont to what I said about sealing up the metal.

Primers are porrus(spelling???) and will not stop water from reaching the metal. Unless you use 'primer/sealer' water can still get to your car untill you lay down the paint. And whatever you do, don't use primer's, sealers, or anything from an automotive department store (ie CDN Tire, Pep Boys). I find they don't cover well, or adhere properly, esp the spray can stuff.