How to clean black greasy residues form re-polishing or from a new pieces of equipmen

:confused:I am trying to clean a 316 SS sampling thief (brand new) for the base line swabs. It is 3 ft long and one side is 12 gauges and the other side of the wand is approx 3 gauge. It has black residues of oil, grease and possibly free iron.
We have tried few detergents, acidic, basic but unable to remove the residues. Any suggestions, how to clean these residues.