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Most drivers focus on the price at the pump, but the type and quality of fuel chosen can have a noticeable effect on a car’s engine. It influences everything from power output to long-term reliability. Understanding what goes into your tank is a simple way to care for your vehicle.
Understanding Fuel Composition
Not all fuels are created equal. Petrol is rated by its Research Octane Number (RON), which measures its ability to resist premature ignition, also known as ‘knocking’. Standard unleaded petrol in Ireland is typically 95 RON. Diesel fuel quality is often indicated by its cetane number, which relates to how quickly the fuel ignites under pressure. A higher cetane number generally means a shorter ignition delay and more efficient combustion.
Beyond these basic ratings, fuels contain a complex blend of hydrocarbons and specialist additives. These additives are often what separate standard fuels from premium versions. They can include detergents to clean the engine, friction modifiers, and corrosion inhibitors, all designed to protect engine components and improve operation.
The Consequences of Lower-Grade Fuel
Using a fuel with an octane rating lower than your car’s manufacturer recommends can cause issues. The engine’s management system may detect knocking and adjust its timing to prevent damage. This adjustment often results in reduced power and less efficient combustion, which can lead to higher fuel consumption.
Over time, poor quality fuel can lead to the formation of carbon deposits on critical engine components.
Citizens Information guidance explains the requirement.
- Fuel injectors: Clogged injectors can disrupt the fuel spray pattern, leading to poor combustion and reduced efficiency.
- Intake valves: Deposits on intake valves can restrict airflow into the cylinders, hampering performance.
- Combustion chamber: Build-up in this area can increase the risk of knocking and affect overall engine health.
For diesel engines, low-quality fuel can contribute to injector blockages and affect the performance of the diesel particulate filter (DPF). This may result in rough running, increased emissions, and dashboard warning lights.
Benefits of Choosing Quality Fuel
Opting for a higher-quality fuel can offer tangible benefits. The most immediate is often a smoother and more responsive engine. The advanced additive packages in many premium fuels are formulated to clean the fuel system.
These detergents work to remove existing carbon deposits and help prevent new ones from forming. A cleaner engine operates more efficiently, which can translate into better fuel economy. While the cost per litre may be higher, some of this expense can be offset by travelling further on each tank. A clean engine is also a healthier engine, potentially leading to fewer mechanical issues and a longer service life.
A Scenario of Unexpected Costs
Imagine a driver who buys a second-hand car with a modern, high-performance engine. To save money, they consistently use the cheapest standard-grade fuel available. After several months, they notice the car feels sluggish and the engine management light appears.
A trip to the garage reveals significant carbon build-up on the intake valves, requiring a specialist cleaning process. The repair bill is substantial, far outweighing the small savings made at the pump. This situation shows how a seemingly minor decision can lead to a significant, unplanned expense, much like facing a repair cost that falls just below a car insurance excess.
Making the Right Choice for Your Car
Deciding on the right fuel does not always mean picking the most expensive option. The first step is to check your vehicle’s handbook, which will specify the minimum required octane rating. For many standard cars, a good quality 95 RON petrol is perfectly adequate.
For high-performance or turbocharged engines, manufacturers often recommend premium, higher-octane fuel to achieve optimal power and efficiency. Understanding the specific needs of your vehicle is the best way to make an informed choice. Considering the long-term health of your engine and the potential for better performance can make a difference. The details of the fuel quality impact can help you decide what is best for your vehicle.
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