Wurth sells a rust-kill product, but its name escapes me. We use it on M-B rust warranty repairs on current production S-class sedans with rusty lower doors...whoever designed the lower weatherstrip on the doors so it traps water was not thinking that day...if it's too bad we replace the door shells and let me tell ya that isn't cheap, becasue on metallics you have to blend the quarters and fenders for color match and you wind up painting most of the car.

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2002 Ford ZX2
2 x 2013 Honda Civics