Hi Everyone ! I have an 2006 A6 and i noticed during the winter months when it is really cold outside and the car has been off for a while , on a cold start it rattles for a quick few seconds and then runs smoothly. I was told by my mechanic that chances are that the timing chain needs to be replaced and to do this repair is a big job that consists of taking the entire motor and transmission out because the chain is on the back side of the motor and he said that the guide on the timing chain doesn't hold it in place and it causes the rattle on a cold start . He said if it skips a few teeth it could blow out the motor . The repair itself is costly and i was wondering if anybody has had this issue? Is it normal to have this kind of maintenance done just in case ? the car has 160000 miles. I know it seems like a lot of miles but everything else is in great shape and maintained .