Just looking for some advice on how to proceed with some emergent rust around doors. I was fiddling around cleaning around door area and I see
How should I clean that up and prevent further rust from forming?
When you see rust around door seams, rust started from the inside. You must spray a penetrating oil inside all doors and I would get whole
car done. Find a local garage that offers an oil rust proofing spray with oil, not wax. Then you can try to repair around the door seams.
If it's just where the outer door skin is folded around the rest of the door, that happens because it's outside the ring of weatherstripping and is basically naked to the elements.
I'd sand off the bad stuff then slow future rust down with an almost-solid wax treatment.
Go here say hi. There's some good how tos and lots of knowledge on those forums.
With door or any other panel look for folded seams especially horizontal ones. Those creases are where evil starts. Dust dirt and moisture collect that's where you'll find rusts beginnings. Door bottoms and fender edges are the usual worst culprits.
Keep those slots on door bottoms front and back flushed out a couple times a year ,send some hose Water in one end do it drains out the other. Clean any debris you see out of the drains so they free flow. When washing Make sure yo flush the underside especially in the rear trunk are.. look at where your plastic inner fender liners meet the wheel arch. If you can flush that out especially in winter . Those things will slow things down as does addressing the tiny rust spots before they bubble into a pit. Just dont expect immortality , rust always wins.
I've read people who live in brine areas (mainly NE), should spray under the car. One product I researched a little but never used is Fluid Film. Our brine (NW) is typically washed out quickly by the next rain.
Once rust starts, it's exceedingly difficult to stop. There are various oily products that can be sprayed into door seams that will displace moisture for a while. However, it's just a matter of time before the rust spreads in earnest. There are also rust conversion products that may be helpful in some situations.
Corrosion X makes a line of products that is commonly used in the aviation industry. The thinnest Corrosion X will penetrate seams and flow into the tightest areas. Corrosion X "MaxWax" is a thicker product that will help seal out moisture with a firm waxy coating. Corrosion X HD is a thicker product that remains wet.
Removal of rust is the only way to properly treat it. Unfortunately, by the time it's noticed, it's generally spread quite far underneath.
Anyone who's watched rusted panels deteriorate will notice how the corrosion tends to form UNDER the paint and existing rust, and travels along both, destroying fresh metal.
Like said, once it's there, aside from replacing the area, all you can do is slow it down. For a daily-driver, I'd knock off loose bits and coat with a POR-15, rust bullet, etc, maybe top coat it to match as best as possible, then use fluid film, or similar in the door cavities.