I have been using some Maxi-Lock (Swirls) serger thread with few issues. I match bobbin thread to top thread and do a sample stitching first. If the sample stitching doesn't hold tension, I make a note and don't try it again. I'm trying to use up thread I have on hand. I mistakenly bought Madiera serger thread instead of Aero-Quilt, although it was a lighter weight I saw no issues with it. Years ago I bought some serger thread at Wmart...can't remember the brand, but think it was Talon and it was a terrible thread and never bought it again.