I am looking to test drive and buy a 2012 Black Edition Audi A5 Auto 3.0 S-Tronic. The car has done 166k on the clock which I know is high mileage but has full-service history with services every 18k at Audi dealer garage. I have been told that I should ask Audi about the chain but they say its not a serviceable part. Then others say that it should be changed with such high miles. I don't know who to believe or what the costs of a change would be. Any help appreciated or things to ask/look out for appreciated.