I've been having very good results with a water soluable synthetic(?) cutting lubricant for drilling, tapping, sawing, knurling and turning on the lathe.. steel, ss, brass and aluminum.
The stuff is marketed by Lenox (a cutting tool brand, band saw blades etc), named Pro Tool Lube. The label states that it contains no silicone, is biodegradeable, and I think the stuff is glycerine-based. It's given excellent performance for all the cutting tasks mentioned above, and it rinses away with water, so I can shoot a stream of water from a trigger-spray bottle into (or thru) holes to flush cutting chips out easily.
There is no troublesome film or oily residue remaining after a plain water flush/rinse. When I want to paint parts that I've used the PTL on, I don't need to do any other preparation, other than what I'd normally do for bare metals.
Pipe cleaners work well, although the ones that are made for crafts seem to be fuzzy synthetic stuff, and not like good 'ol fashioned pipe cleaners. Gun cleaning bore brushes are handy too, and there are solvent-proof brushes for cleaning the siphon tubes of paint spraying guns.
I get the Lenox PTL at Fastenal.
WB ......... metalworking projects