What is your washing routine on your dirty microfiber towels? I wash my car about every 3-4 weeks or so with my spotless wash system. Usually, I end up using 1 towel to dry (just the black roof). Might use a cheap microfiber towel ever month or two covered in chemicals for cleaning the leather or something. Seems like I shouldn't wash the 2 together, or with other clothes, or 1 at a time in the machine. Maybe a hand wash? Thoughts?