I'll admit I got a little taken in on this car, its pretty much rust free from the top of the rockers up but pretty heavily rusted from the rockers down but only about 4 inches wide, the bottom of the car is actually pretty good.
To start I took the wire wheel on my angle grinder and ground off some surface rust. I started at the front of the car on the driver's side working from the rocker up so just above the really bad part.
Once I ground off the rust back to clean metal I brushed on some POR15. I'm using their gas tank sealer because I had some. I like using the gas tank sealer because its very thin and brush strokes are pretty well hidden.
So then I'm left with a choice, the surface rust is stabilized and while there aren't any holes underneath I know that there will be holes soon and since winter is on its way this problem will become very bad by next year and that will ensure this is a three year car, maybe even just a two year car. So after a lot of debate and some poorly considered fiberglass I went to the hardware store and bought some new cutting wheels. So with my new cutting wheels I sliced out a 4" x 12" segment from the front of the car and welded in a piece of old computer case. I like working with old computer cases because the metal is very dense, this is because we'd like to have computer cases be non-magnetic. This is actually some of my better welding, I wish I'd gotten a picture. Its a LOUSY place to weld, I jacked up the car and got a stand under it but I still had to lie on my back and weld up, the outside wasn't bad but the inside was a drag. Once that was done I ground down the welds and wire brushed the whole thing before brushing on more POR15. In a couple places I filled in little holes with fiberglass and more POR15. It would have been very hard to weld behind the front fender and I didn't want to go through pulling the fender. Maybe next spring I'll have a chance.
So anyway I figure this side of the car needs 2 more feet of 4" wide on this side and if this side needs it I'd bet the other side needs it too. Thats probably going to use up this whole computer, fortunately we just replaced our microwave and I'm told old microwaves make good repair metal too.