After we got our high efficiency, front-loading washer, I realized that it said to NEVER use anything but high efficiency detergent.
I called the manufacturer, explained that I wanted to use milder washing agents for my quilts and asked if using something like Retayne or Quilt Soap occasionally would harm the washer.
They said it WOULD and it could void the warranty.
OK, I admit that I still sometimes use it, but I make sure that I have a good reason, and I don't use it just to pre-wash fabric or to wash a quilt.
But when I do wash quilts, I use a VERY little bit of HE detergent instead of the recommended amount. So far, everything has worked out fine.
BTW, if I had to do it over again, I would not get this kind of washer. Instead, I would get one of the new, higher efficiency top-loaders which don't have these requirements!
BethMI