Originally Posted by TheMerkleFamily

I've not had a problem with any threads on my Bernina 770QE - 12wt to 100wt, cotton, poly, etc.. I typically use various weights of Aurifil and I really like Masterpiece by Superior Threads for piecing (a 50wt cotton). OMNI 40wt poly by Superior Threads works wonderfully, too. By comparison, your Bernina will require a bit more effort to clean & oil in the bobbin area, regardless of what thread you use.