I don't know why but PBW just seems to work a leeettlle better than oxyclean.
PBW contains sodium metasilicate.
OP:
If you can find it, unscented powdered automatic dishwaser detergent is a much more powerful cleaner than Oxyclean (it is very close to PBW in chemical composition). Oxyclean is basically sodium percarbonate and sodium carbonate (a.k.a., washing soda, which is a water softener). Powered automatic diswasher detergent contains sodium metasilicate (although the manufacturers generally use the family name, which is sodium silicate). Unscented powered automatic diswasher detergent was my "go to" cleaner for years until it became difficult to find.