If your noisy clutch release bearing becomes quiet its about to give up.
 

When i bought my present car the clutch required attention as the pedal was on the floor, i fitted a new clutch and release bearing about 3.5 years ago.
Less than a year after fitting it started whining when the clutch pedal was pressed but didnt get any worse with use and recently got quieter which i was happy about for a month or so.However when i arrived at work the other day and drove into a parking space the pedal went to the floor and i stalled it on the brakes.
I drove home with no clutch which was not great fun and have just stripped the gearbox out to find the release bearing has seized and melted the plastic body
and im now wishing i had changed the release bearing during the summer when it was noisy.

I changed my CDT's clutch earlier this year, and among the preparatory reading on here, I found posts, describing members experience with dry, new release bearings, easily determined by spinning the bearing to test, before installation. A well greased bearing will not spin freely (and noisily), but should turn easily, smoothly and quietly ( as indeed mine did), with only the resistance of the lube contained within it. I would advise everyone doing their own repairs to check new parts for grease under the rubbers, as too often, I have found the merest drop under them, and half the bearing faces dry of any lubrication. I would have sent them back, if I didn't have the car already in bits. Lesson learned, order the parts early, if it's a problem you have known about, and planned time for, so you can check them before you start disassembly.

That was the annoying thing about it, when fitted it felt nice and smooth and quiet but became noisy after a few months and so i had to put up with it .I got used to it and although i intended to replace it i never got around to it and was happy when it became quiet.
What i assume happened is the bearing seized and the the heat caused melted the plastic innards leading to leaking out of the fluid.
I have nearly finished replacing the complete clutch and just hope the bearing in this one lasts but dont have much confidence in aftermarket parts for these cars nowadays.