A rattle can will give you a crappy job, Maaco will do it better in that case. Buy a cheap spray gun and compressor, the results will be much better. Or you could just brush on Rustoleum as said above, it won't look perfect but it will stop the rust. On a $250 car who cares if the paint is messed up.

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2006 CL500
2009 C300 4matic
1969 280SE
2023 Ram 1500
2007 Tiara 3200