How can I clean my bath tub?

I have an ordinary porcelain bath tub, green colour. I've been using it for 10 years now. It has developed some stains over the years, that won't come out, like rust, etc. If I use Strong detergents, the bath tub will lose its shine. What can I use?How can I clean my bath tub?
Try using powdered Tide. It is gentle cleaner but a little abrasive too. My husband uses this for everything, like washing his hands after he works on greasy cars. We even used it to wash our boat in the summer.How can I clean my bath tub?
Try putting some bleach in some water in the tub. Let it soak for a while and rinse. The stains should be gone. I have a tourquois color tub that is over 45 years old. I have been cleaning it with WD40 every day. No smell, it's not slippery and you wouldn't belive the shine! Just wipe it out with a paper towel. hope this helps you out.
Soft Scrub is pretty good for the tub.
CLR gets rid of all hard water stains.... can usually find it at any department store, or hardware store.
I like cleaner by the name of Bon Ami - It just like Comet but without the chemical smell