I'ma long-time A4 owner, in both B5 and B6 guises. I'm looking at buying a B7 in the next few days, and don't expect too many surprises. The only thing that will be new to me is that it is a 3.0 V6 TDi. Are there any reliability and/or servicing concerns specific to this particular engine that I should be looking out for or asking questions of the seller about? Thanks in advance.