CNC Machines and Metal working Machines including lathes, they have many complex moving parts. These parts create friction and require oil to keep them functioning properly. However, not just any oil will do for a lathe machine. Specialized oils are needed, and they must meet specific standards set by the International Standards Organisation (ISO). To ensure the smooth operation of your lathe, you need to determine the viscosity required for your machine and find an oil that meets that standard.