150 - 200mg/wk of deca is considered to be a therapeutic dosage. And will help lubricate the joints nicely.
Keep in mind, you MUST run testosterone along side the deca, as a base to the cycle, to ensure sex drive/mood, etc...
You could run the same sort of dosage of test (IE) 100 - 200mg/wk... which is basically a TRT dosage, or just above that.
-VM