I have a year 2000 Astra 1.6 Club. Recently when starting from cold there has been a gentle squeaking noise (more like creaking) from the engine compartment at idling speed. The noise only lasts about 15 seconds after starting and doesn't happen when the engine is warm. It doesn't sound like alternator belt squeal, but I could be wrong. It's hardly a 'problem' as such (yet), but I'd like to identify where the sound is coming from and sort it out. Has anyone else encountered this?