I use 3 vibratory tumblers daily. Lyman 2500 Magnum's. I rebuild Mopar door hinges and when the parts come from the manufacturer after heat treating they are dark and covered in oil. I Use Purple Power , less than $5.00 a gallon at Wal-Mart and let the parts sit in a bucket of it for 1/2 hour. Use heavy , long rubber gloves. This stuff is strong!! If the coating is real tough, a Scotch-Brite pad takes it right off. This keeps from contaminating the tumbler media so it will last longer. I have one tumbler full of Coarse Walnut shell, one with fine Walnut shell, and the last with treated corn cob. I spray a little Weimans Stainless steel cleaner in it from time to time. The parts come out with a high polish finish. This does not clean threads. A s/s wire toothbrush sized brush cleans the threads without damaging them. If you use a wire wheel on your bolts it is potentially dangerous if it slips out of your grip and it damages the threads. If these are not critical bolts... but if you need them to stay tight, pass on the wire wheel.