Depends on what you expect a tapping/cutting fluid to do. Most of
them simply carry away heat, either through flooding and convection,
or through evaporation (energy absorption due to change of state). A
few, like the old Rapid Tap that had 1,1,1-trichloroethane in it,
actually created a thin oxide layer on the tool as soon as the tool
got hot, and that oxide acted as the lubricant. The trick was to use
only a drop so that the tool would get warm enough. Too many folks
would flood it and the effect was lost.
Of course, like anything that works well, it was outlawed, in
this case because it affected the ozone layer. I don't know if the
"new" Rapid Tap (must be 17 or 18 years old now) does the same thing,
but it looks more like oil and doesn't work as well. I still have half
a can of the old stuff that I use only on the toughest cuts.
WD40 or kerosene or anything like that (I use Mouse Milk
sometimes) will evaporate quickly and cool the tool. Makes less mess
than having to flood it. The messiest stuff I ever used was a green
goop that resembled yogurt that worked ok but left scum and lumps all
over everything. Can't remember the name of it.