Types of oil

Essential oil

An essential oil is a concentrated, hydrophobic liquid containing volatile aroma compounds from plants. An oil is 'essential' in the sense that it carries a distinctive scent, or essence, of the plant. Essential oils do not, as a group, need to have any specific chemical properties in common, beyond conveying characteristic fragrances. In history, oil has been used by Vikings, Spartans, etc. in war as they believed it made them stronger.^{[citation needed]}

Essential oils are typically extracted by distillation. Other processes include expression, or solvent extraction. They are used in perfumes, cosmetics and bath products, for flavoring food and drink, and for scenting incense and household cleaning products.

[edit] Mineral oil

Mineral oils, found in porous rocks underground, originated from organic material, such as dead plankton, accumulated on the seafloor in geologically ancient times. Through various geochemical processes this material was converted to mineral oil, or petroleum, and its components, such as kerosene, paraffin waxes, gasoline, diesel and such. These are classified as mineral oils because they do not have an organic origin on human timescales, and are instead derived from underground geologic locations, ranging from rocks, to underground traps, to sands.

Other oily substances can also be found in the environment; the most well-known of those is asphalt, occurring naturally underground or, where there are leaks, in tar pits.

Petroleum and other mineral oils (specifically labelled as petrochemicals) have become such a crucial resource to human civilization in modern times they are often referred to by the ubiquitous term of "oil" itself.

[edit] Organic oils

Organic oils are also produced by plants, animals and other organisms through organic processes, and these oils are remarkable in their diversity. Oil is a somewhat vague term in chemistry; instead, the scientific term for oils, fats, waxes, cholesterol and other oily substances found in living things and their secretions, is lipids.

Lipids, ranging from waxes to steroids, are somewhat hard to characterize, and are united in a group almost solely based on the fact that they all repel, or refuse to dissolve in, water, and are however comfortably miscible in other liquid lipids. They also have a high carbon and hydrogen content, and are considerably lacking in oxygen compared to other organic compounds and minerals.

[edit] Synthetic oils

Synthetic oil is a lubricant, consisting of chemical compounds which are artificially made (synthesized) from compounds other than crude oil (petroleum). Synthetic oil is used as a substitute for lubricant refined from petroleum, because it generally provides superior mechanical and chemical properties than those found in traditional mineral oils.