The "old" Coats & Clark Dual Duty Thread
I have used it on several quilts that are over twenty years old that have been washed multiple times.
The thread does not cut into the fabric - as some people have "supposed" it would.
I have no idea where that myth came from - but my experience with that thread is that is works fine.
At the time, I had no knowledge of the other "good/better" brands of thread available. I did know that there were some "cheaper" - lesser quality - brands around that were easily available.