Rust spot drivers side rear passenger door sill.

I rubbed mine back with the little wire brush from a touch up then treated it with a rust inhibitor the touched it up.

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Find source first (if underside, then need to rust-proof that first!)

Else as Simspj says "rub down to no rust, rust proof/inhibitor, then sand to smooth, primer/undercoat/topcoat if necessary ..."

Epoxy (or etch primer) as rust inhibitor if rubbed down to bare metal.

Been doing a bit of this under where the mudflaps sit and done as above. Sanded effected area, primer (mine has zinc in it), few coats of primer to build it up. Been drying for days to make sure it's proper hard and next I'm going to fine wet sandpaper it to smooth, touch up (just a brush will be fine on that small area), on mine the patches are a bit larger so may wet paper first couple of coats to get a nice finish and then good few coats of lacquer for future protection. Bit of a novice at this myself but think I'm going in the right direction. Will probably put flaps back on anyway just didn't want the beginnings of the problem getting worse. I'll also treat the inner lip of the arch, will just rust treat and zinc primer that bit though I think.

doesn;t worth the work if you do no prime it

Edited 5 May, 201511 yr by IulianE

A dremel with a small grinding wheel would be great for this.

Take a dremel to it till its bare clean metal. Then filler prime paint and lacquer. Doing the same to mine. Had to replace half the sill on both sides too

Im lucky mine have survived scot free!