Oilslick spawns from the non-kos blobs just south of the succor point in Steam Factory. When you go south from the succor point, you'll quickly reach a bridge. Jump off the bridge and there are six non-kos blobs down there. I've seen it spawn twice from one of the three south blobs, dunno how to narrow it down any further than that since all three of them roam around.
Foundry Master spawns in that big "Foundry" area in the north part of Steam Factory, no idea which mob the PH was though. I believe it was a roamer, but don't hold me to that.