Hi mate, i have washed mine twice in the machine on cool wash with regular washing powder, then i have just hung it for a couple of days to drip dry. There's no problems with threads or inner lining comin undone etc. Just make sure its cool wash.
Never washed a rubies Vader before but I use the dryel system on my costumes. Just throw the costume in the dryel bag with one of the cleaning sheets and throw it in the dryer. All my costumes come out smelling nice and fresh everytime. I got mine at Target. Hope this helps.