I put my metal parts in really hot water. If I remember correctly it was boiling. Everything pretty much cleaned itself.
Romans 1:16 I am not ashamed of the gospel, because it is the power of God for the salvation of everyone who believes: first for the Jew, then for the Gentile.
I boiled all the parts from my Eddystone. The stuff floated. I let it cool a bit, then slowly poured it through some paper towels (you don't want that stuff in your pipes. I guess you could toss it outside though).
Then I cleaned as normal. No biggie.
I was having issues with mine.
Completely stripped it, and found cosmoline, cordite, brass flecks, and crud all in it (previously owned). Soaked the parts mineral spirits, and she ran like a charm.