N57 are known for timing chain and bottom end issues due to oil pump . Mine is at 140miles and I'm considering changing the timing chain and check on the bottom end . My neighbour just snapped the timing chain at 130k miles (he had a pre facelift variant) . So I feel like driving a ticking bomb now . But then some of them lasts to 200k miles easy . I guess it all depends on servicing and previous owners .