it wont last for very long. if it is mild or aluminized steel, which is most oem exhaust systems, your probably going to be repainting it. i know with my current jeep, when i did my exhaust which is mandrel bent aluminized steel i used rustoleum stove and bbq paint, brush on in fact and that was 3-4k miles ago. i've had good luck with it on many exhaust systems that i have build over the years. just make sure you prep the metal first. wire wheel/brush, and some light sanding and you should be good.