By Steve Reeder
There was a time when crude oil was regarded as little more than an unpleasant, smelly nuisance.
Ancient civilisations had known about naturally occurring petroleum for thousands of years. The Babylonians used bitumen for construction, the Egyptians found various uses for petroleum products, and people in different parts of the world discovered that the strange black liquid seeping from the ground could be useful for waterproofing, sealing and, presumably after considerable experimentation, making a terrible mess of your sandals.
Nobody, however, had yet worked out how to turn it into a global industrial empire, but that changed rather dramatically in the 19th century with the birth of modern refining.
Although crude oil had been used for centuries, the beginnings of the modern petroleum industry are generally associated with the development of commercial oil production and refining during the middle of the 1800s.
One of the crucial developments was the realisation that crude oil wasn’t a single substance. It was a mixture of hydrocarbons with different boiling points and properties. Heat it carefully and the various components could be separated.
This process – fractional distillation – became the foundation of petroleum refining.
In 1856, Polish pharmacist and inventor Ignacy Łukasiewicz helped establish one of the world’s first modern oil refineries in what is now Poland. Around the same period, the famous Drake well in Pennsylvania began producing commercial quantities of crude oil in 1859. The resulting petroleum boom initially had relatively little to do with automobiles.
The star product was kerosene/Paraffin.
Kerosene provided a relatively clean and efficient fuel for lamps and was rapidly replacing whale oil as a lighting fuel. Petrol, meanwhile, was not exactly the jewel in the refinery crown. It was considerably more volatile and, before the arrival of the petrol engine, had relatively limited value.
Then history produced the internal-combustion engine, and suddenly that inconveniently volatile fraction of petroleum became extraordinarily interesting.
From crude oil to a refinery
Early refineries were comparatively simple. Crude oil was heated, and fractions were separated according to their boiling ranges. But the rapidly expanding automobile industry created a problem: demand for petrol began growing much faster than simple distillation could conveniently supply it.
The answer was to stop merely separating hydrocarbons and start changing them, and this is where modern refining really began to become clever.
Thermal cracking was developed commercially in the early 20th century.
Instead of simply taking the molecules that happened to be present in crude oil, refiners discovered that large hydrocarbon molecules could be broken into smaller ones using heat and pressure. That meant heavier fractions could be converted into lighter, more valuable products such as petrol.
It was a wonderfully practical solution. If the crude oil wasn’t giving you enough of the molecules you wanted, you simply started rearranging the furniture.
Catalytic cracking took the idea considerably further. Developed commercially in the 1930s, catalytic cracking used catalysts to break and rearrange hydrocarbons more efficiently and selectively than purely thermal processes.
The modern refinery was becoming less like a giant kettle and more like a chemical factory.
Further developments introduced processes such as catalytic reforming, hydrocracking, alkylation and hydrotreating. These allowed refiners to improve fuel quality, remove impurities such as sulphur and produce increasingly precise hydrocarbon mixtures.
By the middle of the 20th century, petroleum refining had become an extraordinarily sophisticated branch of chemical engineering.
And then there was the problem of lubrication.
Keeping the machinery alive – An internal-combustion engine produces an extraordinary combination of heat, pressure, friction and contamination. Essentially, we took controlled explosions, put them inside a metal box and then expected the machinery surrounding them to survive hundreds of millions of cycles. Lubrication was therefore rather important. Early lubricants included animal fats, vegetable oils and relatively simple mineral oils. Petroleum-derived mineral oils eventually became dominant because they could be produced consistently and in enormous quantities.
But as engines became faster, hotter and more powerful, ordinary mineral oil began reaching its limits. Lubricant chemistry consequently developed into a specialised science. Refiners learned how to improve the quality of the base oil by removing undesirable compounds. Chemists then added substances designed to perform very specific jobs.
Detergents helped prevent deposits. Dispersants kept contaminants suspended rather than allowing them to form sludge.
Antioxidants slowed the chemical breakdown of the oil. Anti-wear additives protected heavily loaded surfaces, while corrosion inhibitors helped protect the engine itself. And then the viscosity modifiers allowed oils to remain sufficiently fluid during cold starts while still providing adequate protection at operating temperature.
This is what ‘Multigrades’ is all about and why Oil Has More Than One Number. One of the cleverer developments in lubricant technology was the multigrade oil. An engine needs oil to remain fluid enough to circulate quickly when it is started on a cold morning, but thick enough to maintain a protective film when the engine reaches operating temperature. Unfortunately, oil doesn’t naturally excel at both jobs.
Multigrade oils solve the problem by using specially selected base oils and viscosity-modifying additives. A familiar 15W-30, for example, behaves broadly like a relatively thin SAE 15W oil during cold conditions, while providing the high-temperature viscosity characteristics associated with an SAE 30 oil once the engine is hot.
The “W” means winter, rather than “weight”, and the two numbers describe how the oil behaves under different temperature conditions.
In effect, multigrade oil gives the engine a lubricant that can dress for winter and summer without requiring you to change the oil every time the weather forecast does something inconvenient. The trick is not that the oil literally changes from one grade into another; rather, its formulation is engineered so that its viscosity changes with temperature in a controlled and useful way. So, engine oil had stopped being simply “oil”. It had become a carefully engineered chemical system.
Then there was the synthetic revolution
The next major step was the development and widespread adoption of synthetic lubricants. Instead of relying entirely on the naturally occurring molecules left over after refining crude oil, synthetic lubricant chemistry allowed manufacturers to create molecules with specific characteristics.
Synthetic base oils can provide excellent low-temperature flow, high thermal stability, strong resistance to oxidation and consistent performance across wide temperature ranges.
This became increasingly important as engine manufacturers pursued greater power, improved fuel economy, tighter tolerances and longer service intervals.
Modern lubricants are consequently classified into different base-oil groups, ranging from conventional mineral oils through highly refined Group II and Group III stocks to specialised synthetic materials such as PAO and ester-based lubricants. And the distinction matters.
A modern lubricant isn’t simply there to make two metal surfaces slippery. It must manage heat, suspend contaminants, protect against wear, resist oxidation, seal combustion gases, remain stable under extreme pressure and continue doing all of that for thousands of kilometres. It is effectively performing several engineering jobs simultaneously while sitting quietly in the bottom of the engine.
And now we have electric cars!
Just when the lubricant industry thought it understood automobiles, along came electrification.
Electric vehicles don’t have conventional internal-combustion engines, but that certainly doesn’t mean they don’t need sophisticated fluids.
Electric motors, reduction gears, bearings and transmissions operate under their own demanding conditions. Some electric-drive lubricants must simultaneously provide gear protection, manage heat and remain compatible with electrical components.
Hybrid vehicles are arguably even more demanding because their lubricants must cope with frequent starting and stopping, rapidly changing temperatures and engines that may repeatedly switch between operating and dormant states.
So the evolution continues. What began with crude oil bubbling inconveniently from the ground has progressed through fractional distillation, cracking, catalytic chemistry, advanced refining and synthetic molecular engineering into something remarkably sophisticated.
The black liquid itself is almost the least interesting part of the story.
The real achievement has been learning how to take an unpredictable mixture of hydrocarbons, separate it, modify it, purify it and ultimately engineer fluids capable of protecting machinery operating at astonishing speeds and temperatures.
From kerosene lamps to turbochargers. From whale-oil substitutes to synthetic lubricants. From simple distillation to molecular engineering.
And all because someone, somewhere, decided that the easiest way to make a machine survive controlled explosions was apparently to invent an entirely new branch of chemistry. So, the next time you check your oil level, spare a thought for the chemists. They’ve spent roughly 170 years making sure your engine doesn’t eat itself. And judging by some of the noises coming from my neighbour’s old Volkswagen, they may still have work to do.