I haven't bought Biz in ages - I'll be sure to try some if I get stains that don't come out.
I use OxyClean powder for soaking yellowed quilts or quilts with water marks.
If the quilt stinks (mold, mildew, pet odors or stale tobacco) I add a cup or two of ammonia to the wash water. Ammonia kills mold and mildew spores and it breaks down oily substances like grease stains or nicotine, but it doesn't bother dyes or harm your quilt. It rinses out cleanly and leaves the quilt fresh and sweet.
For blood or grass or some unknown stain, I use the non-aerosol spritz-on Shout that's made for set-in stains.