Subject: A question regarding oil

I have wondered for a long time: why does oil float on water? It is denser 
than water as is iron,lead etc. Then why? Does it have anything to do with 
solubility or miscibility?  And what exactly is the relation between density 
and the upthrust force IF the upthrust force is responsible for casuing 
something to float or sink?  In our country not many books are available to 
consult and your site is my last hope. Please help me out.

Re: A question regarding oil