11-The Milling Machine - Milling Machine Oil Pump
Some machines are equipped with oil pumps (most are manual) that include an oil reservoir with a level sight glass. These are sometimes called one shots because it takes only one pump of the handle to lubricate the knee, saddle, and table. They distribute lubricant through a series of tubes to strategic locations throughout the machine.
In the video, notice that the level is now at mid range between the minimum and maximum. To add oil, unscrew the cap and use a funnel to fill with machine oil. Re-screwing the cap, you can see that the level is now at the maximum. Pump the handle a few times after filling with oil. After that one pumping motion should be sufficient.
You will need to refer to the owners manual of the machine to find out how much, when, and which kind of oil or grease your machine needs.