I had a Viking branded Tin Lizzie. The thing I really liked about it was that it would take any thread. 40 wt, 50, 60 70, metallics, really anything! I just matched the needle size to the thread, used a 16 with the thinner weights. I also matched the bobbin thread to the top thread (except when using metallics). I got an additional bobbin case and set one for 40 weight, and used the other for thinner threads. This is how I set the tension:
https://www.youtube.com/watch?v=Q1mRhcquZTM
Although I used all different brands, I usually used Connecting threads Polyester Pro or their essential cotton.