In this handy guide, you will get a quick glimpse into the different worlds of each of the most common fuel types that we see on the roads today. It will help to provide an understanding of each of the fuels and help you further understand how they work and their history.
What is diesel?
Diesel is a byproduct of fractional distillation of petroleum that burns off at a lower temperature than gasoline, making it a “heavier” fuel. It burns differently because of this variation in production. Diesel is ignited using air compression and diesel injection as opposed to gasoline, which requires a spark plug. Other heating techniques are employed to enable ignition in colder climates.
Prior to 2016, the majority of diesel sold in the UK was a conventional, high-sulfur fuel. However, starting in 2016, the majority of diesel sold in the UK, the USA, and northern Europe was an Ultra Low Sulfur Diesel, which had been modified to have a greater positive impact on the environment.
As opposed to gasoline’s Research Octane Number (RON), diesel is measured by a Cetane Index and Number.
What does cetane mean?
When diesel fuel is pumped into compressed air, the rate at which it ignites is measured by a cetane number. The higher the cetane number, the quicker it ignites. The EN 590 rules state that diesel must have a minimum cetane number of 51. Standard diesel engines typically perform best at a cetane number between 48 and 50, however some high-performance vehicles benefit from premium diesel, which can reach 60.
Cetane index is the other figure that affects a diesel’s quality. Diesel has a number of different types, similar to the multiple numbers that apply to gasoline. The density of the fuel and the distillation range are used to calculate the diesel cetane index. It’s important to remember that a diesel cetane index is an addition to the cetane number and is meant to aid in understanding quality rather than to determine it.
The whole diesel market was impacted when the dieselgate emissions scandal broke in September 2015, not only Volkswagen and its affiliates. It was discovered that between 2009 and 2015, Volkswagen had installed “defeat devices” for pollution on millions of its vehicles. In industry experiments, these devices were developed to mask genuine emissions, but in field tests, the emissions might be up to four times the legal limit.
Along with having a terrible impact on VW, the larger diesel market also suffered as a result of people’s diminished confidence in diesel vehicles. NOx emissions from diesel vehicles cause ammonia and particulates, which harm the environment and are more harmful than CO2. Due to the overwhelming opposition to diesel automobiles that resulted from this information, the UK government declared that starting in 2040, no gasoline or diesel vehicles would be permitted on the road. This announcement caused a pushback from automakers in favor of electric vehicles. To remain competitive in the future, most automakers are currently making electric vehicles.
Prices and diesel history
In the late 19th century, Rudolf Diesel was looking for a fuel to power his combustion-ignition engine when he discovered an application for diesel. He began by powering it with coal dust, then tried several fuels before settling on diesel.
Due to the business margins involved, diesel is more expensive than gasoline. Simply put, gasoline dealers raise the price of diesel to increase their profits since so many commercial customers use diesel vehicles and because commercial drivers prefer diesel. Considering that diesel is more cost-effective and has a higher MPG, it generally offers a better value per mile.
What is unleaded?
Through a procedure known as fractional distillation, petroleum is converted into the product known as petrol. Petroleum, which must be separated using what is referred to as a fractionating column, includes crude oil and many other fuels. Petroleum is discovered while drilling for oil, and it is then extracted and refined to create a variety of fuels, including gasoline, kerosene, and chemicals needed to make plastic. Global oil consumption is thought to be over 95 million barrels per day.
Diesel engines operate differently than gasoline ones. The fuel in petrol engines is ignited by a spark from a spark plug, making them spark ignition internal combustion engines. The knocking sound is made when the ignition starts too early or at the wrong moment. If you discover it, inform your garage so they can advice you on what to do next as it might seriously harm the engine.
Even though it is derived from the same underlying material as diesel, the petrol we see on the forecourts is a petroleum-based product. Depending on their resistance to autoignition, different types of gasoline are rated and given octane numbers.
What does a rating of octane mean?
The octane rating of gasoline is a gauge of how well the fuel prevents engine knocking. Knock happens when the cylinder’s fuel-air mixture explodes rather than burning steadily. Within the combustion chamber, this shockwave travels and produces a metallic “pinging” sound.
An “anti-knock index” is another name for an octane rating. An engine will be less likely to knock if the fuel has a high octane rating.
How do octane numbers work?
All types of gasoline typically have an octane number in one of three ranges. Under extremely controlled circumstances, a 600 RPM test engine is used to measure the Research Octane Number (RON) of gasoline. The Motor Octane Number (MON) of gasoline is calculated under more demanding test settings with a hotter and faster engine.
The Anti-Knock Index (AKI), which averages the RON and the MON, is another option, however it’s mostly utilized in North America and other places. To further complicate matters, the AKI is often referred to as the Posted Octane Number (PON).
The Observed Road Octane Number, which is tested on actual multi-cylinder engines typically at wide open throttle, is the last type of octane number. Testing of this nature has been practiced since the 1920s and is still valid today, almost a century later. This was initially carried on on roadways, but to improve the accuracy of the results, it was moved to testing facilities.
A short history of petrol pricing
The first modern combustion engines were developed in Germany in the late 19th century, and they ran on a fuel that was relatively volatile and had a boiling point 40 degrees lower than our present petrol. Better fuels that boiled at much higher temperatures and hence “knocked” less over time as knowledge and science advanced made cars more dependable and petrol the primary fuel source for most of the world’s cars.
In the UK, unleaded petrol was first supplied in 1988 after the EEC, the EU’s forerunner, warned against using leaded petrol.
When petrol first went on sale in 1896, a gallon of it cost the equivalent of £9.00. These days, prices are much more expensive and unstable.
How do premium fuels work?
Super unleaded and premium diesel, which together make up premium fuel, are seen as a luxury since they make us feel better even though they don’t necessarily give the automobile a worthwhile benefit over time.
What distinguishes premium fuels from regular fuel?
Super unleaded has an increased knock resistance due to its greater octane level than unleaded. Super unleaded typically has an octane value of 98–100, whereas unleaded typically has a rating of 95. Those who own high-performance cars and some hot hatchbacks will most frequently detect this higher-performance fuel.
When you fill up your car with premium fuel, you’ll find that the throttle response is better, the engine will rev more easily, and the engine should produce more power. Even though these vehicles were designed to run on unleaded, it will be worthwhile to fill up with super unleaded for longer trips or roughly every 1,000 miles to give the engine an extra push and maintain it operating at its best.
Premium diesel sometimes has a greater cetane rating than regular diesel, which causes it to ignite more quickly when injected into the engine’s compressed air. Since diesel engines are now so meticulously made, the greater cetane rating may not always imply anything to the engine.
Utilizing a premium diesel will only improve your car’s engine cleanliness. In the long run, cleaning up the engine and removing any leftover soot or particulates can be accomplished by using a premium diesel every 1,000 miles or before a stretch of numerous lengthy trips. Even while the upfront cost can seem high, employing this approach will help you save money in the long term by extending the engine’s life and lowering the frequency of engine maintenance and repairs.
Because premium fuels cost more to produce and need more time to engineer, their higher prices elevate them to the status of luxury goods.
Worth the extra cost?
It’s quite rare that you’ll require premium fuels unless you have a sports car that the manufacturer recommends for premium fuels or you need to clean out the engine. In fact, several manufacturers have stated that using premium fuels won’t benefit the engine and you should stick to the standard. Few engines truly require premium fuels; most are designed to run on regular fuels.
It will be worthwhile to occasionally fill the tank with premium fuel because the long-term advantage of a cleaner engine and a decrease in soot in a diesel will undoubtedly help. In a petrol car, using super unleaded after traveling to a country where the octane rating is lower than in the UK will assist to restore your car to normal, but using premium fuels every day is just impractical and not cost-effective.
Don’t use premium fuels often unless you’re totally flush with cash, have a high-performance car, or both.