As in the title, my S3 suddenly started making one hell of a whistle noise when driving this morning, down the motorway, its so loud i can hear it from inside. when its at ~1000-3000 revs its most frequent. When i get to my destination, and put it into neutral (or just depress the clutch), it starts doing this... (annoying kid on trampoline in background in case your wondering what the other sound is) Under the bonnet... Also worth noting the noise about 4 seconds after starting the engine, and 4 seconds after switching off... Some friends and most internet diagnosis is looking towards the PCV valve and / or hose, or fuel pressure sensor. It is booked in for a major service and cambelt change, however this only started happening today, on the way to a quick KFC lunch... As im looking at around Â£700 for cambelt + service, I could do without another big hole in my pocket. Thanks for any help, Jordan EDIT*** Ive lost a good litre of oil in about 2 weeks... ive read that if the PCV valve is broken, it forces oil out and causes oil leaks?