JIMinPHX, I'll have to respectfully disagree with you on the engine oil thing.
I actually agree with Willbird, in that you are better off with nothing (turning dry) and taking your time about it.
I have used the stuff (engine oil) , and found it so lacking as to amount to being a detriment to progress.
But, if it seems to be workin' fer ya... Probably somewhere near the origins of the phrase "your mileage may vary" came from, eh.
A guy could do worse things than to try it and keep an open mind. I'd suggest trying it up against some of the other options, to see what works and what does not, though. Mmmmm! Bacon! :)
Cermet's eh? Never touched them.
The day I showed an old friend of mine how much nicer mild steel cut with a brushed on bit of soluble, though, I could have named my price for the bottle! He was using WD40 and whatever else he had around the farm shop, including engine oil, and had always figured that oil was oil... You could clearly see where the soluble mix had been applied in the progress of the cut. The finish went from horrid to pretty decent.
If I am turning fast enough that the brushed on application does not stay put, I either need a flood system, or I need to rethink my strategy, but brush application is great for the slow, fine cuts that are for finish, usually, in a home shop. Business wise, if a guy has to consider whether brush application of a substitute for a proper coolant is a good idea, well, that business ain't gonna be around for long anyways, so... Home shop stuff should run at a different pace. The priorities are to enjoy oneself, as well as to make whatever one is trying to make, rather than to see the best cash return for ones time investment.
The 5 gallon bucket for flood coolant is a great system, if your machine has a tray to catch the drippage, and the location allows you to splash a little around from time to time (domestic bliss isn't improved by stained ceilings, any more than by stainless swarf in the living room carpet, BTDT!). Even a gravity feed drip system or a squirt bottle is better than nothing, if you can use the help of a cutting fluid. I've seen one system where the guy used a homebuilt "bilge pump" style pump to transfer the coolant up to his header tank, a 2 gallon bucket with a soldered on fitting. Lotsa ways to skin that cat.
Dairy creamer (not the "edible oil product" stuff, real cow) works pretty darn good for tapping copper, as well as for turning commutators. Just gotta lay out a couple paper towels to catch the drips, and rinse or wipe the parts down. That animal fats thing again.
I like beeswax for tapping and drilling, if I cannot get any tapping juice. Run a wad of beeswax down the hole and the chips get pushed up as the tap goes down, then the remnants come out when you remove the tap. Works great!
We use beeswax a lot for drilling out stainless and titanium rivets, too. Really improves the drill life! Just drill into the block, then to the job.
Cast Iron and brass are best turned dry, and wearing eye protection (which you should be anyways!) for the flying dust and chips. Good cast iron is a joy to machine, but filthy, and poor cast iron, is pretty much the exact and total opposite, full of hard spots and inclusions. Most brass is as nice. Some of the bronzes are decent, some will make you want to take up other hobbies.
Anyhoo. Sorta rambled on a bit... Hey. It happens! :D
Cheers
Trev