Ha Ha!! I've been using some of my GRANDMOTHERS thread, and she died in 1973 (and probably didn't do ANY sewing for at least the last 2o years of her life)!! My H-Viking isn't fussy about thread, can mix and match no problem, but my Janome is another story. It has to be the "good" stuff and it has to be the SAME stuff top and bottom otherwise it vomits.
Old thread is also great for binding.
Sue