Sometimes, chemicals are added to normal oil to give it special properties. A lubricant, like motor oil, can also help in reducing heat. Simply put, cooling depends on surface area in contact. So, if something normally has a small surface area, you can put that thing into a bigger pot, and put oil in the pot. This way, oil comes in contact with small surface area of the small object, and transfers that heat to the big surface area of the big vessel. As a rule, liquids can transfer heat better than gases.