I have a 17 3.0t premium with 57k miles. I noticed I was having to add coolant fairly often but what got my attention was when the heater would blow cold air when I was at a stop. The reservoir was empty and I ended up putting 3/4 of a gallon in it. That was about a month ago and Ive put almost 2k miles on it since and its empty again. Ive got an appt to drop it off Wed. Ive read several cases of people with the same problem and getting a new engine. Wish me luck whatever it may be.