Cutting fluid (Emulsion) is a type of coolant and lubricant  designed specifically for metal working  processes. There are various kinds of cutting fluids. They may be made from petroleum distillates, plant oil, water and air, or other raw ingredients.
Most metalworking and machining processes can benefit from the use of cutting fluid, depending on work-piece material. Common exceptions to this are cast iron  and brass , which are machined dry.

There are generally three types of liquids:

  • Mineral emulsion
  • Semi-Synthetic emulsion
  • Synthetic emulsion

Semi-synthetic and synthetic cutting fluids represent attempts to combine the best properties of oil with the best properties of water by suspending emulsified oil in a water base
These properties include: rust inhibition, tolerance of a wide range of water hardness ,ability to work with many metals, resist thermal breakdown, and environmental safety.
Water is a good conductor of heat but has drawbacks as a cutting fluid. It boils easily, promotes rusting of machine parts, and does not lubricate well. Therefore, other ingredients are necessary to create an optimal cutting fluid.

Mineral oils, which are petroleum-based, first saw use in cutting applications in the late 19th century. These vary from the thick, dark, sulfur-rich cutting oils used in heavy industry to light, clear oils.
Semi-synthetic coolants, also called “soluble oil,” are an emulsion or micro-emulsion of water with mineral oil. These began to see use in the 1930s. A typical CNC machine tool usually uses emulsified coolant, which consists of a small amount of oil emulsified into a larger amount of water through the use of a detergent.
Synthetic coolants originated in the late 1950s and are usually water-based.

The Toodle may use each type of emulsion to drive the turbine.
For calculating turbine rotation speed, we assume 95% water (viscosity and density).