I have an Audi A6 Avant 2.7 TDi Quattro (2010) with the automatic tiptronic gearbox. With 60,000 miles on the clock, I have started to get a short squeak when changing from third to fourth. Sometimes it happens from fourth to fifth. It only does this once the engine is up to temperature and U have also had some short lived vibration around fourth and fifth gear. Any ideas as to the cause? Would changing gearbox oil do any good idea - there is no schedule in the service booklet for tiptronic gearbox oil changes.