What?????? You smeared stuff on the rust to hide it? You gotta be kidding! ;-D

There is only one way to deal with rust on a car. Fix it! This requires bodywork (all rust removed down to the bare, clean metal), holes filled with a suitable compound, priming, and repainting) done by a professional (unless you're really good at such work yourself). I get a local guy who works out of his home to fix any early rust spots on my old car long before they get a chance to rust right through or spread very far. You cannot allow rust to spread, because once it gets going it spreads fast, like a cancer.

But, hey...if you want to go the cheapest route possible...just put duct tape over it! ;-D It'll last a few months.