I have used olive oil or olive/canola-mix for a while in drilling, tapping and reaming because I have some sort of allergy and get a nasty rash immediately if using "normal" cutting oils or sulfurized gear oils.
Seem to work as well as average cutting oil. Wipe clean after use and occasionally give the tools a squirt of WD-40 or way oil and wipe clean to prevent polymerization and getting your tools "varnished"
But the canola oil makes the shop smell like the local burger joint french fries...
I think next time I have some nasty stainless to tap I'll try this handy lard packed in a tube: