So I'm finally tackling the rust on my 94 DX. I already took care of the wheel arches, but the rockers down by the bottom corners of the rear doors are pretty bad. The previous owner just filled them with bondo and never even painted them.

Is there a common cause for rust in this location (water/salt coming in from somewhere not obvious)?

I don't want to fix it and just have the rust back again in a few months.

 

the water would run down and sit in that area to cause rust. I see you're up north so it's expected.

Seal the inside and it will last longer.

 

Gotcha! That would explain it. I wasn't sure if the water was getting in from inside and rotting it from the inside out. I have another car that I get that with.


I'm wondering if it would be worthwhile to make a drain hole or two in the plastic rocker panel cover.

 

Nah, the plastic piece is just the outside cover. It's actually inside the subframe where the water/condensation sits.

 

Mostly then I would probably blame the P.O. for not washing the salt off good in the winter.

I have two identical cars (94 Oxford Blue DX's). One with 225k and one with 120k on the clock. The higher mile one is perfect, the 120k mile one is the one with the rot. Go figure.