If you need lubrication and less cooling use a neat cutting oil. Conversely if you need cooling and less lubrication use a water soluble oil.

With carbide tooling I tend to cut dry; it saves throwing coolant all over the workshop. However I use coolant for parting off, with most HSS tooling, on the CNC mill and for grinding. After extensive research I selected BP Hysol XF as a general purpose soluble oil coolant. It is primarily designed for low/medium alloy and stainless steel, but is also good for aluminium. It's not so good for brass and not recommended for magnesium. It is also good for a range of applications including turning, milling and grinding. I use it on lathes, manual and CNC mills and grinders. I have had no problems with corrosion and no nasty smells despite the coolant sitting for weeks or months at a time.

It is also usable in hard water areas.

I usually keep the concentration at around 6%, checking on a regular basis with a refractometer.

Andrew