On 2010-09-03, poachedeggs wrote:
I thought I'd had a bad fan in my semi-homebuilt pc. I was getting a
terrible few minutes of noise, what seemed like friction buzzing/
grinding sound. After repeated oiling over a few weeks did nothing or
only solved - or more likely seemed to solve - the problem for a day,

What is this "oil" you speak of?

If you say something like WD40, then that's your problem.