Does anyone know a good product for cleaning old coins?

Soak in Coca Cola overnight, then polish with Brasso. The results are amazing.

If you think you are going to make them look better to sell, sorry, but any cleaned coin is worthless. DO NOT DO IT! Any value a coin had would be lost if you cleaned it. If you want to clean it for some other reason, and I can't think of any, just spend them and be done with it. Take them to the bank and change them into new shiny coins, if that is what you want. But never ever clean old coins!!

A reputable coin dealer will cringe at your question. You will absolutely reduce a (collectible or valuable) coin's value if you clean it. It you send the cleaned coin in to a grading service to be "slabbed" (professionally graded, and then sealed in a plastic case along with a hologram and a unique ID for that coin) they won't even accept it. If I'm not mistaken most of these company's websites (PCGS, etc.) are very clear about this in their information section.

I assume you're not a serious collector/trader? I just thought cleaning old coins actually reduces their value.

Silver coins can be safely cleaned in under an hour in a dish of lemon juice + iron nails.

You can clean copper coins with harpic or coca cola

coke is really good but i've always wondered why people need to clean their coins.

pepsi for removin (chemicals makes the dirt dissolve) -tooth paste for shinin

*let it sit-in the pepsi for couple of hours

leave them in a glass of coca cola.