Once fender rust appears, is there anything you can do besides replacing the entire panel?

What would you do, retard?

You cut the rust out and weld in new metal.

>retard
This, from a guy that thinks filler on a hole is a good repair.

Slap a thicker piece of metal on there and blast it with rust inhibitor/piss

Please don't speak in image macros, we're not on reddit.

You don't bondo a car you want to keep.

how does the metal on the car rust if theres paint over the metal?

You need to use a rust converter or sealer after you're done removing the damage or you'e going to be one of those retards that's astounded that the rust came back.

in older cars, like old hondas, a design flaw means moisture builds up behind the quarter panels and eventually rusts from the inside out

yes you can buy a non GM car

Do you mean pre-rust or after rust?

If its painted properly and the paint is never pierced then it wont - but it only takes a microscopic hole for air and water to get in. It then starts rusting beneath the paint, and usually only becomes visible after it has started to really eat the metal

Throwing paint ontop of metal doesnt work as you have too many "sharp" edges and particles where those holes will be, aswell as the fact that paint doesnt latch to rusted metal for shit

Wtf are you on about.

Sand down and remove all rust. Spray primer. Spray paint.

It's not difficult.

Jesus it's not hard at all.

>grind off lightly rusted sections
>cut out rotted sections
>if the holes are 2 in or less use bondo fiberglass to fill
>bigger ones need welded, or if you're a nigger like me just use JB weld and steel mesh, then bondo
>sand smooth
>paint

Bondo fiberglass is no joke, patched a rust hole on my truck door, and I'd be willing to bet that it's stronger than the rest of the door.

Buy a welder if your car is rusty. You will need to patch new holes every other month.

If its not visible body rust just sand down to new metal and slop some por 15 on it. Legit the best shit for rust ive ever used. (Been doing this shit for 20 years)

PRO TIP

Wash the car before the cold weather sets in, and leave it dry. Around Oct/Nov. Grab a container of Vaseline. Spread it around the bottom of the doors, rockers, and the wheel well lips. It goes on clear. LEAVE it for the entire winter, it will eventually turn black after catching debris. When washing in winter don't touch the area. This forms a protective layer of greasy protection.

Once the spring hits and it gets hot enough, it will start to melt off (15C). At this point its time for removal, you soak it in degreaser, blast most of it off with a pressure washer, and hand clean off the rest. Those areas covered in Vaseline never saw an ounce of salt the entire time. The doors and front fenders on my 1994 Protege are still new because my mom owned this car and did this for 13 winters from 2003 to 15/16. The back wheel area did get a little rust, but its just bubbles at this point. Its also a good idea to blast the rear bumper attachment point often with a good oil, like Krown T40 spray, too keep rust minimal. And keep up on your touch ups! Have a good eye, and touch up areas inside too like the bottom door and trunk seams for example. Catch it early, blob some paint over it, and you're good.

I bought a 1990 Mazda 929 in 2006 with light rust around the rear wheels. I painted over it and slobbed Vaseline on it that is left on all year (this car does not get winter driven). It more or less has the same grease on it 11 years later aside from reapplying when it melts off a bit in the summer. The rust underneath it didn't get better, but it didn't get any worse.

Grease, oil, and keep an eye on things and you too can have a 25 year old shitbox still look decent.

>is there anything you can do
Rinse off the salt from the bottom of the car on a regular basis. When the rust gets hold, you have to clean it even more diligently because those spots become weak spots for expansion of rust.

>how does the metal on the car rust if theres paint over the metal?
A chip in the paint allows moisture to soak down to the metal. Rust happens. That rust breaks the bond of the primer to the metal at that spot and becomes bigger and bigger. Because rust bulges out, it is like a dome under the paint that retains water each time water gets absorbed. Thus, the rusting continues even though it is a sunny day because you have water trapped under the paint.

Sharp edges of painted sections often have the paint being thin or worn off. Thus, water can enter the seam between paint and metal at that point. Or there is flexing trim that has rubbed a hole in the paint. Since fender trim holds water that adds to the problem.

>eventually rusts from the inside out
A classic inside-out location is the bottom drain of doors. Rust begins at the bottom there and spreads across the insides. Salt and other minerals get trapped and form deposits inside, so the concentration of salt might be pretty high in there.

Don't buy a Mazda unless you live where it never snows.

>only an issue for 2 years
>on 2 cars
>over 10 years ago.
>mazda fixed the issue for free
Try harder

Those early Mazda3's at ten years old have more rust than 90-94 Proteges in the early 2000s.

This started around the time the Protege5 hatch came out. 2002-2003 P5s were garbage in 6 to 7 years. Mazda really went south with corrosion practices. Mostly every 2004 to 2008 Mazda 3, sedan or hatch, has advanced rust.

Only 04 and 05 3s were affected.
Proteges had issues to but not near as bad as people like to meme.

>Once fender rust appears
You have to remove it before repainting. Any bubbled areas need to have the paint removed from those spots too. You can't paint over rust because you don't have a bond to metal.