[abdulloh]

How is the performance compared if we using engine oil in place of the oil part of the cutting fluid ingredient, worse, as good as, or better ?

[Enthalpy]

Both need about the same qualities. But very different cutting fluids exist, with extremely varied viscosity, so one won't replace them all.

In Germany, we even use ethanol to cut aluminium. In France it's rather light petroleum.

But to cut a thread, you need a huge viscosity. The fluid drops slowly from a brush. This results logically from the very slow cutting speed and the high contact pressure. Some powder (C, MoS₂) in a grease should logically be even better, but people use very thick oil.

So motor oil should intuitively excel to mill or turn steel, but be inadequate to bore anything, chip aluminium, cut threads...

Then you have special requirements. Some metals oxidize easily and give a nicer aspect if the fluid protects them against air and does not oxidize the metal. Other ignite easily (titanium!) and you strongly prefer non-flammable fluids with these.

[salmawisoky]

Using engine oil as a replacement for the oil component in cutting fluid is not recommended and is generally not as effective. Cutting fluids are specifically designed for metalworking processes, such as machining, drilling, and milling, where they serve multiple purposes, including lubrication, cooling, chip evacuation, and corrosion prevention. Drift Boss

[Bevisflyn]

Using engine oil instead of oil in a cutting fluid is usually worse. Engine oil does not have the ability to cool and lubricate as well as cutting fluid, which can lead to overheating and increased tool wear. It may be good enough in some cases, but is generally not optimal for machining processes.

papa's scooperia