I use most any kind of thread in my Singer machines including the featherweight... However, I use ONLY SINGER NEEDLES in them too. There is something about the shank that makes the Singers not like the other needles no matter what the package says. Usually for my piecing I will use a 80/12 or 90/14... On the machines I actually quilt with I use 90/14 Embroidery or a 100/16... Still Singer needles.