Fuel and Your Car: A Short Guide to Refuelling

The UK’s driving population is booming, with over 1.5 million new cars hitting the roads every year. As more and more new drivers acquire vehicles, many find themselves on the roads without knowing the basics of how their car works. Understanding fuel can be important to new drivers – especially in cases of ‘misfuelling’.

The Difference Between Petrol and Diesel

Petrol and diesel are both a form of fossil fuel, derived from crude oil – which itself comprises a mixture of hydrocarbons with different chain lengths. Petrol is a collection of hydrocarbons with between 5 and 12 carbon atoms in them, while diesel comprises hydrocarbon chains with 12 or more carbon atoms. These longer chains are heavier, resulting in a higher boiling point. Petrol and diesel behave differently, as do the engines powered from them; diesel, owing to its greater density, acts simultaneously as a lubricant, and is injected into compressed air before ignition in the engine. Petrol is less dense and ignites via spark plug with no need for compression.

What If You Put the Wrong Fuel in Your Car?

Diesel engines make the most of diesel’s lubricative qualities, making using the wrong fuel disastrous to its operation; misfuelling diesel engines with petrol can cause moving parts to seize if the engine is engaged, starting with the fuel pump. Petrol engines can also seize if fuelled with diesel, as a result of the heavier diesel simply clogging up moving parts.

If you have reason to believe you have mis fuelled your engine, do not turn the ignition. Starting the engine will force more fuel through it, potentially increasing the amount of damage it does tenfold. Instead, call a roadside maintenance service to come and flush your engine on your behalf.

Filling Your Car Safely

The first step to safely filling your car with fuel is to check the fuel your car takes. There are several ways in which this can be done. You can check your car’s service manual for information on the kind of engine or look at the inside of the door to the fuel cap for a sticker denoting the fuel type required. There are also tell-tale signs elsewhere in the car. Your dashboard may reference the fuel type required – or your rev counter. Diesel engines run at lower RPMs than petrol engines, and your car’s rev counter will reflect this. The red zone in a diesel car’s rev counter will start at a lower RPM than in a petrol car.

Safely filling your vehicle involves more than ensuring you use the right fuel; petrol or diesel spillages can result in hazards in petrol stations and on the road. Fuel is very slippery when spilt, and extensive leakage can result in instability on the road, presenting danger for cyclists and motorcyclists. As such, careful filling of your vehicle at petrol stations is key to prevent unnecessary spillage – and ensuring your MOT is booked online can make certain that your fuel tank and exhaust are checked for holes and potential leak points regularly. When filling your car, ensure you keep the fuel nozzle tip several inches within the opening, and fasten the filler cap securely when you are finished filling the tank.