Oil is a relatively thick, viscous liquid produced from crude oil, plants, animals, or chemical synthesis. Oil and water don’t mix (usually). A lubricant is any substance that serves to reduce friction between moving parts. There is a lot of overlap between the two.Most oils are lubricants. The oil creates a layer of liquid that prevents contact between solid surfaces, which dramatically reduces friction. But not all oils are lubricants:
- Vegetable oil is used in cooking, to soften and flavor food and as a heat transfer medium.
- Dielectric oils, which fill electrical transformers, are used to carry away heat and insulate against electrical arcing.
- Hydraulic oil is a power transfer medium in heavy machinery, so you have oil in a hose instead of a drive shaft or electrical wire (although lubricity is usually also important in hydraulic systems).
- Most lubricants are oils. The chemical properties of oil — low volatility, high lubricity, low freezing point — make it excellent for use as a lubricant. But not all lubricants are oils:
- Teflon coatings reduce sliding friction and sticking in mechanisms (and cookware). This is longer-lasting than a film of oil.
Graphite powder is a dry lubricant used where liquid lubricants are undesirable or unreliable, like lock mechanisms and mechanical clocks. Liquids add viscous drag to small moving parts.
Grease is usually made from oil, but is thickened into a paste or gel consistency so it will stay in place and not run off of parts