I've been doing a bit of reading as my engine sounds a bit diesel-ey. Not excessive, but enough to search the forum and find all the other threads where people are saying the same thing.
I read on a Seat (Boo, hiss!) forum someone said it is the strainer/oil pick up which is partially blocked which causes lower than ideal oil pressure which can make the chain noisy?
My car is on just over 100k so I was thinking of cleaning the strainer as preventative maintenance anyway, but has anyone found this quietened down the timing chain a bit?