IndigoBlueWagon
TDIClub Enthusiast, Principal IDParts, Vendor , w/
N57 is a good engine. Same one as in the 335d and X5d, with minor differences. The emissions hardware can be problematic, and it's expensive. For example NOX sensors (there are two) are closet to 700 each. But the engine is smooth, quiet, and pulls like a train. The 335ds can have carbon biildup problems (mine hasn't), but I don't think that's true in the heavier X5 and 535. It's a small car/big engine issue.
If the car has received a new DEF tank in its life it's probably OK for a while.
If the car has received a new DEF tank in its life it's probably OK for a while.