Crude oil can be sweet, sour, heavy, or light depending on its density and chemical composition.

The mixture is primarily composed of molecules of carbon and hydrogen atoms bonded into a variety of shapes and lengths, giving each different chemical properties, such as boiling points. Refining can remove elemental impurities—such as sulfur—after hydrocarbons are separated, ensuring the resulting products can be used effectively in other machines, such as car engines.

Technically speaking, crude oil is unrefined petroleum. This article dives into the different ways it’s categorized (by density, sulfur content, and origin), and how the combinations of these types of oil are used.

Brent, West Texas Intermediate, and Dubai are the three crude oil classes and differ in terms of typical refinery uses, density, sulfur content, and suitability for financial benchmarking. Brent, which originates in the North Sea, is traders' go-to benchmark, in part, because it is easily shipped and politically stable, and used to price most of the crude sold internationally.

More than 85% is refined into fuels, such as gasoline and diesel, while about 10% is converted into raw materials for plastics, synthetic rubbers, and other essential products, such as lubricants. Because the majority of these products are less dense than the starting crude oil and additional inputs are introduced during the refining process, there is a processing gain of three gallons.

More than half of the US’s oil is exported as the country produces mainly light, sweet crude but has many refineries that handle heavy, sour types.

Crude oil processing produces a variety of fuels and the building blocks for plastics, but it also distills out the hydrocarbons used to make aspirin, Teflon, vinyl, crayons, candles, Tupperware, roofing shingles, asphalt pavement, hair dye, anesthetics, food-grade lubricants, polyester, synthetic rubber, and resins for items like dentures.

The 1859 oil discovery in Titusville, Pennsylvania, sparked a boom in oil exploration and production to meet the demand for kerosene lamp fuel. Because the 42-gallon barrel was a readily available container already in use for shipping fish, butter, wine, and other goods, it was adopted by the Petroleum Producers Association in 1872 and by both the US Geological Survey and the US Bureau of Mines in 1882.

Before advancements in fracking technology made lighter shale oil readily available, US refineries had been built and optimized for decades to process heavier oil from other countries with high profitability. Despite being able to refine lighter oil, US oil companies can operate with better margins by exporting it to other nations whose refineries are optimized for it and importing heavier oil, for which the US has the infrastructure.

The oil industry is broken up into the upstream, midstream, and downstream segments, and oil refining is part of the latter. “Downstream” refers to companies like Standard Oil that are converting crude oil into a finished product.

In fact, the US has been exporting more oil and petroleum products than it imports since August 2021. Petroleum and petroleum product exports totaled about 10.7 million barrels per day, whereas imports totaled about 7.9 million barrels per day.

The abiogenic petroleum theory holds that fossil fuels originate in Earth's mantle and are constantly replenished, rather than formed by microorganisms over millions of years. While inorganic chemical processes can produce simple hydrocarbons, the range of complex molecules found in crude oil suggests an origin from a diverse set of organisms. Isotope analyses of these molecules also support the model that they originated from living things that preferentially take up certain isotopes over others.

Most types of plastic are made from polymers derived from chemicals produced by the processing and refining of crude oil and natural gas. Spikes in the cost of either fossil fuel raise the cost of wrappings, tubs, and other plastic containers for products.

Sweetness levels are determined by the amount of sugar added to the wine at the end of the process—anything up to 6 grams per liter is extra dry, and up to 12 grams per liter is still considered dry.

When analyzing the production of crude oil, shale oil, oil sands, and condensates since the start of the 20th century, Saudi Arabia produced more crude oil only in 1977, from 1979 to 1981, and from 1991 to 2016. Nations such as Iraq and the United Arab Emirates produced much smaller quantities than both Saudi Arabia and the US.

Oil dependence began with the rise of oil as a commodity, followed by an era of geopolitical competition for the resource after World War II. The domestic fracking boom, which started around 2006, was driven by a desire to reduce the nation's dependence on international adversaries for energy.

Oil passing through the Strait of Hormuz makes up only about 7% of US crude imports. However, crude oil prices account for 51% of the cost of a gallon of gas in the US. US refiners pay the Brent crude futures price, even for domestic drilling.

This guide explains how investing in oil works with in-depth explanations of each of the forces that control oil’s price. Oil is unique as a commodity in part because of OPEC’s role in regulating its price.

Experts say oil demand has not yet reached its peak. Recent technological breakthroughs in the oil industry include advances in drilling and extraction, as well as subsurface technologies.

Studies show that microorganisms in chicken manure can break down the hydrocarbons in crude oil without producing toxic by-products. Scientists have also explored avoiding the environmental risks of chemical dispersants and synthetic adsorbents by using human hair and peat moss to adsorb crude oil, which can be taken up by their cuticles and porous structures, respectively.

This animated map video vividly illustrates how petroleum shaped global politics and industry—from 18th-century uses and 19th-century drilling booms in North America to today’s OPEC strategies, shale revolution, and geopolitical oil influence.

Oil spills from oil tankers—which can have a sharp, short-term impact on oil prices—have become increasingly rare over the decades in part because of stricter regulations.

This method forcibly extracts fossil fuels from tightly packed rocks, where they form from organic matter that has undergone extreme heat and pressure. Conventional drilling, on the other hand, waits for the oil and gas to escape from shale and accumulate in more porous and permeable rocks, such as limestone.

Requirements for traffic plans, access roads, and noise barriers vary by state and local laws, but once the rig site is prepared, the rig is assembled and digs a well that is then encased in steel and cement to protect groundwater reservoirs. After drilling and testing the extraction pipe, fracking fluid is injected into the rock to create cracks where crude oil resides, allowing it to be pumped out.

Specifically, a country’s “spare capacity” signifies the difference between its maximum sustainable oil production and its current output. OPEC member countries hold nearly all of the world’s spare oil production capacity. Historically speaking, Saudi Arabia has been the country with the largest spare capacity.

Scientists compared the smells of babies and teenagers and identified some of the compounds that make teens smelly. Carboxylic acids present in teens, they wrote, seemed to give off an "earthy, musty, or cheesy" scent. This 2024 research could help inform future odor-control products.

This tracker shows the current price of common commodities such as crude oil, lumber, nickel, and many more, as well as how much these prices have fluctuated over the past day, year, week, and month.

Essential oils are a big business, with industry estimates pegging its market size at $10B last year—a number expected to double by 2030. These distilled plant compounds have a long history of both legitimate and exaggerated uses, and many marketed oils are, as the author of this long read claims, just selling wish fulfillment. Revisit some of the history and contemporary use of essential oils with this piece.

Developed to reduce the volume of goods—thus lowering storage and shipping costs—the concentration process uses pressure and heat to remove water, pulp, and skin from fruits. Concentrates provide significant flavor, sugar, and calories to foods in small quantities, but do not retain most of the fiber, vitamins, and other nutrients from the source fruit.

This episode of The Rest Is History podcast traces oil's pivotal role—from fueling industrial growth to steering imperial power. It also examines how access to oil shaped US politics, World War II, and sparked the creation of OPEC following the Suez Crisis.

Mexican Coke is sweetened with cane sugar (sucrose), which dissolves into equal amounts of fructose and glucose, whereas American Coke, which uses high-fructose corn syrup, contains more fructose than glucose.

Fracking technology has significantly increased how much crude oil the US produces. As more countries adopt fracking technology, there could be an increased downward pressure on prices—although fracking has been widely criticized for its negative environmental impacts.

Oleogustus is Latin for "a taste for fat," and researchers proposed in 2015 that it should be accepted as the sixth basic taste. This article teases apart exactly what it would take to officially be considered the sixth taste and why researchers think the fat taste may be a strong candidate.

The US has a Strategic Petroleum Reserve that it taps into, releasing barrels into the economy, during times of emergency (think: major storms and wars) to try to stabilize markets.

Texture is the brain's interpretation of several sensations, including pressure, as registered by our teeth, tongue, and finger tips, and sound, as recorded by our ears. Texture also speaks to food particle sizes—smaller than 35 microns contributes to the sensation of creamy—and the balance between flavor and mouth time, such as the crunch of a crispy chip or the bounce of a chewy caramel.