Retayne is used to permanently set dye in fabric. You use it on individual fabrics or fabrics in a color grouping. I personally do not usually use Retayne. If a fabric bleeds enough to require it, I don't use that fabric in a quilt.
Synthrapol is used after the quilt has been made. It suspends loose dye particles in water so they don't create a "bleed" in other fabrics.
Domestic front-loader washing machines do *not* use enough water to make either Retayne or Synthrapol effective. They also do not provide enough water to dilute dye bleeds. I have a small front-loader and I always take my new quilts to the laundromat for their first wash. I use the largest front-loader at the laundromat.
You can use a domestic top-loader washing machine to prewash fabric as long as it uses enough water to dilute bleeding dyes. Fill with water and add anything you are going to use, *stop the machine*, add your fabrics and use a sturdy dowel (a couple of bucks from the hardware store) to push the fabrics down and around. Manual agitation like this is much easier on the fabrics/quilt than using the machine's agitator. Advance the machine to the spin cycle and and allow rinse water to fill the tub. Again, stop the machine to hand agitate, advance to spin cycle. Machine agitation cycle is not safe, but machine spin cycle is. Be sure to immediately dry the fabric; do not allow damp fabrics to lie against each other as dye can transfer through this kind of contact too. This is a way to prewash fabric without getting your hands in the hot water.