Only had the S4 a few weeks and has been in (under Audi warranty) for rattle at idle. I also thought i had been losing boost so suspected turbu wastegate actuator spring. Boost has come back with clean bill of health and rattle attributed to knackered water pump which was replaced under warranty. They asked if i wanted to do the timing belts and tensioners at the same time for cost of parts only which i took them up on. I only got it back last night and the rattle has certainly gone. I took it for a long fast run and noticed the oil temp gauge was showing over 160. Redline for this gauge is 180 this sees ridiculously high to me. It came down slightly to 120-140 after 10 minutes steady driving. What do other S4 owners get when driven normal.ly and also driven hard?