Spotlight on: Petrol (fuel)

All motorists know that petrol or diesel are the energy supplies to their car and that without one or the other, their vehicle will quite simply not move.

Gas Station Refill Hand and Nozzle

Petrol and diesel both fundamentally work the same way by burning inside the combustion chamber of the car’s engine. This explosion pushes the pistons down , which results in motion – in other words, the car moves. The only real difference is how the fuel is ignited – in a petrol engine the spark plugs start the combustion process and in a diesel, the compression of the fuel creates the heat which causes the combustion.

The fuel level detection in almost all cars is automatic. Whether it’s a flashing light or a persistent beep every time the car’s engine is switched on, all cars alert, (or annoy) their owner to the fact that more fuel is required.

While most motorists experience low fuel levels, there is a great deal of uncertainty over just how much petrol there is left and how many miles that equates to. The response to how we react to the low fuel light/beep also divides us; there are those who head straight for the nearest petrol station as soon as they are alerted to the low fuel situation, convinced that their car is working on fumes alone. At the other end of the spectrum is the driver who sees the low fuel warning sign as a challenge – a challenge to stretch the last drops of fuel as far as they will possibly go, perhaps for that one last trip to the shops, or to work.

So, just how much fuel is left when the low fuel light or beep comes on? The answer to this is specific to your model of car, and how you drive it.

Most car manufacturers’ handbooks state that once the low  fuel alert has come on, there are typically between 1 to 2 gallons remaining. Of course, translating this into miles depends on your car’s fuel efficiency, but if your car gets on average 40 miles to the gallon, then you have 40 miles left, providing you drive sensibly.

You should be checking your fuel levels regularly and making sure that you have enough fuel for any journey you are about to embark on. An empty fuel tank can end up picking up all the crud which accumulates in there increasing the chance of a blocked filter and leading to potentially costly repairs.

If you do notice you are low on fuel while in the middle of a journey, make sure you visit your nearest petrol station. When you arrive at the petrol station – do be careful because there are some important issues to be noted if you ‘miss-fuel’ your car, which means accidentally adding diesel to your petrol engine, or vice versa.

Should you fall victim to ‘miss-fuelling’, you won’t be alone: the AA reports that every year in the UK, 150,000 people ‘miss-fuel’ –that’s one driver every 3½ minutes. And many of them will end up having to fork out for costly repairs.

You may not realise that filling a petrol engine with diesel is more difficult to do than the other way round because diesel nozzles are bigger than their petrol counterparts. However, it’s not impossible.

Adding the wrong fuel to your car causes a range of damage, including affecting fuel injectors, pistons, fuel pumps and engine filters. All of these can be expensive to repair or replace.

So, what should you do if you realise that you have ‘miss-fuelled’?

It is absolutely vital that you DO NOT start your engine. If you do this the fuel circulates around the car’s engine system, making it far more difficult to remove easily and cheaply.

However, if you have started the engine, it is important to stop as soon as possible, pull over safely into a suitable spot, and turn off your engine.

You should then call a trained mechanic, who can help you by draining the incorrect fuel, repairing the damage and refilling with the correct fuel.  You can find the nearest Trust My Garage approved workshops which do offer roadside maintenance, at our website at

Petrol is just one element of your car that you should be checking at regular intervals. An easy way to remember what maintenance checks you should carry out on your car, is the acronym POWER. In this acronym, P stands for petrol, O stands for oil, W means water, or coolant levels, E is for electrics and R stands for rubber, or in other words, your tyres.

About trustmygarage

TRUST MY GARAGE (TMG) is a scheme developed for independent garages by the Independent Garage Association (IGA) to recognise the high standards of independent garages throughout the UK.

Posted on February 17, 2014, in car maintenance, Motoring, Trust My Garage and tagged , , , , , , . Bookmark the permalink. Leave a comment.

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