Petrol in a Diesel Car in The Close: How Worried Should You Be?
If it has not been started, worry far less than you likely are. Everyone in The Close starts with "have I ruined it?", and the fair answer is usually no: petrol resting in your tank of any diesel remains harmless until priming, cranking or driving pulls it into the system. Petrol in Diesel is who to ring, with the motor kept off, and so it remains that way. Read on for three things: the effect petrol has inside a diesel engine, the clues of how far it has got, and the way to make sure you don't do it again.
Petrol in a diesel: what does it do to the motor?
Two jobs fall to diesel on its route through a motor. Before it combusts, it protects — and then it combusts. What stops the surfaces inside your high-pressure pump and the injectors from grinding against one another is your diesel passing through them — they're made to very fine gaps.
Petrol does the first task badly and the second not at all. The clattering comes from petrol being designed not to ignite when compressed, which is precisely the opposite of what a diesel needs. On top of that it is runnier than diesel, it strips away the protection the system depends on, and any pump working on that mix is wearing itself.
Put those together and the shape of the trouble is clear. Contact does not do the harm — movement does. All a tank with petrol in it amounts to is a fuel fault. Whatever a worn pump sheds travels on, borne by the fuel, into the injectors further along, which is why a pump that has been working on that petrol is where a mechanical fault starts.
How serious is petrol in a diesel? Four situations our engineers see in The Close
Fuelled but never started — the best it gets. On a forecourt, and truly only there, the petrol is still confined to your tank — because anywhere else the vehicle was driven to reach it. The task is emptying and flushing on the spot.
Ignition on, or started for a second. With your system primed, your lines and filter already hold petrol that came from your tank. Normally little more than draining, purging and sorting your filter, and so still easy.
A couple of miles driven, and your pump has spent every one of them labouring on weakened fuel. The work is your tank, the fuel lines, the filter and fresh fuel through the whole circuit, and how hard the vehicle was driven counts as much as how far. On the school run to St Richard's Catholic Primary School, the distance is small. Very different again: a trip to Chichester, under a mile away, or some mileage on the A3(M), under 15 miles from The Close, where the engine never stopped working hard.
Driven on till it complained — rattling, smoke, an uneven idle, a soft throttle. The fuel isn't behaving like diesel any more, and the engine is telling you. Leave it wherever it stops: a lay-by, a side street, the verge on West Pallant. A vehicle stopped quickly very seldom has lasting damage, since the fuel drain and the flush-through, which still come first, sort it out.
The Close people and that petrol in a diesel stories they hear
It will not be fine. The myth: "Fill it the rest of the way with diesel and it will be." Nothing is removed by topping up — you are left with a fuller tank, still the same mix. Percentage is not how a diesel fuel system tolerates petrol, whatever that advice assumes.
If anything, the opposite is true. Myth: "A current diesel can cope with a bit of petrol." Protection matters more on newer diesels, not less, since their fuel passes through finer components at higher pressure.
This is the one that fools people. Myth: "If it starts and drives, there's no harm done." Feed diesel to a petrol engine and it usually will not run, so the motorist stops — and the harm stops with them. Nothing looks to have happened when a diesel fed petrol fires up, ticks over and drives away, which it usually does; meanwhile the pump wears. Running doesn't mean fine.
Myth: "Add some two-stroke oil and drive the vehicle home." It's an old workaround for a separate fault. It doesn't put back what petrol has weakened, and that petrol is still in the tank later on.
Myth: "Drain that tank yourself and you're sorted." After the motor has run, some of the petrol is no longer in your tank: it's in the filter and the lines, and it goes straight back through the pump at your next start. And, a can of petrol filled by the kerbside is truly dangerous.
Petrol in a diesel: how does it happen?
A careless moment is rarely the cause, and no one means to do it. The forecourt makes it easy: the petrol nozzle is the smaller of the two, and it slides into a diesel filler with almost no resistance, while a diesel nozzle generally won't go into a petrol motor at all. So the slip runs one way.
Habit and your car falling out of step is how it occurs. Courtesy car, hire car, or a car that is new. Households running one of each, petrol and diesel. A forecourt you know, but with its pumps arranged differently. Fuelling up in a hurry on the way to Chichester, with a train to catch. The first fill-up in a diesel Volkswagen Golf after years of driving petrol is precisely the moment it happens. Throw in rain, a phone call or a back seat full of kids, and your hand does what it has always done.
The Close motorists: how to avoid petrol in a diesel next time
- Not every forecourt in the UK follows green for unleaded and black for diesel, even if most usually do. Check the petrol pump's label; the colour is only a clue.
- Many vehicles state the fuel inside the filler flap or on the cap, and so check there on the first fill in any vehicle you do not know.
- Good intentions do less than a sticker or a fob in a bright colour on the diesel's key if a house has one of each. So label it.
- Say it before you lift it. On your first fill in a new or hired car, say "diesel" out loud before you lift the nozzle off the petrol pump. It seems silly and it works.
- Mistakes like this are simple to make while your mind is on something else, and so the phone goes away.
- A misfuel inhibitor helps, up to a point. Some diesels have a filler built to refuse a petrol nozzle, and add-on devices are available for vehicles without one. They are a backstop, not a reason to stop reading the petrol pump.
- Less petrol means a thinner mix, and so stop as soon as you notice — though remembering that your next step is unchanged. It is still not to start the car.
Petrol already in a diesel around The Close? Begin here
Short and simple, then, is the order of things. Do not fire it up, and do not switch the ignition on. If you're still on the forecourt — Esso or anywhere else — ask the attendants to help you roll it away from the pump. Ring 0333 366 0103 next, with three facts — the fuel, the approximate volume, and whether it's run.
AdBlue, not petrol? Then say so. Corrosion and deposits, not lost lubrication, make it a separate issue — The Close has a page all for it.
One petrol in a diesel job around The Close costs more than another. Why?
Four different tasks lie behind the four situations above — which is why there's no honest single price. What shifts the cost is mostly which of them you're in. The ratio counts next, meaning how much of your tank is petrol, followed by the position of the car and whether reaching it is safe for a van.
What went in, how much, and whether it's run — three queries we ask before quoting, not after, for precisely that reason. A range turns into a straight figure once the answers are in.
About The Close itself
The Close is a suburban area situated on the outskirts of Chichester in West Sussex, with a riverside setting and an elevation of around 17 metres. The Close is characterized by its predominantly flat housing stock, which reflects the area's relatively low-lying terrain. The Close is located close to the city centre of Chichester, with nearby neighbourhoods including Whyke and Stockbridge. The Close has a population of approximately 5433 residents.
The Close and West Sussex: where our fuel drain cover reaches
Chichester, Whyke and Stockbridge are among the spots near The Close that the same vans work, answering petrol in diesel jobs across The Close's PO postcode area. The car does not need to move to us: our engineers drain at a forecourt, in a supermarket car park, in a lay-by or on your own drive.
Still at the pump around The Close?
The best position there is, then — that's where you are. Turned off it stays; then ring.