When I worked in a quilt shop a few years back, we sold Husqvarna Viking machines and were told by the rep. that European made machines need to use European made threads because of the way the threads are twisted and dyed mwhich is the oposite (the twist) from the American made threads. The European made machines are designed to specifically take European made threads. I use Gutermann, RA, Mettler,Sulky, and some others that don't come to mind right now. My FW will use most anything..bless her sweet little heart! You can have the same problem with needles...I use Klasse' and Schmetz in my HV machines and my Janome and Singer in my Singer machine.