I use a home made coolant / lubrcation on all my CNC metal works, it helps the carbide bit always cool and clean and stay on a needle sharp state for hours of work without having to resharpen them, save you time trying to take out the bit just to resharpen them, I squirt on the working spindle once in a while so that the work path is always soaked.
Sorry for the controller, im playing a game while working on a CNC......just kidding, it`s my remote control for the CNC for loading materials, feed rate adjustments, XYZ etc.
cooking oil + kerosene (50/50)