How Worried Should You Be? Petrol in a Diesel Car in The Burroughs
Provided it hasn't been started, worry far less than you probably are. "Have I ruined it?" is the first thing everyone in The Burroughs asks, and the honest answer is usually no, because petrol resting in a diesel tank harms nothing till it is drawn through the system — by ignition priming, by the starter, or by being driven. Leave the engine off and phone Petrol in Diesel — that keeps it like that. The rest of this page explains what petrol actually does to a diesel, how to tell how far it has got, and how to make sure it doesn't happen to you a second time.
What petrol in a diesel does to the engine
Passing through a motor, diesel does two jobs at once. Before it combusts, it lubricates — then it combusts. What stops the surfaces inside the high-pressure pump and the fuel injectors from wearing down against one another is your diesel passing through them — they are made to extremely fine gaps.
Petrol does the first job badly and the second not at all. Being less viscous than diesel, petrol strips away the protection a fuel system needs, so a pump on the mixture to wear itself. It's also made to resist igniting under compression — the opposite of what a diesel needs — which is why you get the knocking.
Together, those leave the shape of the problem plain. Contact doesn't do the harm — circulation does. All a tank with petrol in it amounts to is a fuel issue. After the pump has been running on that petrol, a mechanical problem has started: whatever is shed by a pump that's grinding is carried onward to the fuel injectors with your fuel.
How serious is petrol in a diesel? Four situations our engineers see around The Burroughs
The best case there can be: filled up, not once started. That petrol is in that tank and just your tank, and the task is a drain and a flush where the car sits. This is the one scenario that can only truly take place on a forecourt, because anywhere else the vehicle has been driven to get there.
Started for a second, or only your ignition on. Petrol has come out of the tank and reached the fuel filter and the fuel lines, because your system has been primed. That's usually still an easy task — a drain, a flush, and the fuel filter seen to.
Some miles driven, and your pump has spent every one of them running on diluted fuel. How hard your car was driven matters as much as how far, and this work takes in that tank, the lines, your filter and fresh fuel through the whole circuit. On the school run to St Joseph's Catholic Primary School, the mileage is short. Any mileage on the M1, under a mile from The Burroughs, means the engine has worked hard throughout, and a run to Westminster, under 10 miles away, makes a very different task too.
It protested, and only then stopped: smoke, clattering, a throttle gone soft, an idle gone lumpy. That is your motor telling you its fuel has stopped behaving like diesel. Stop wherever you are — the verge on Sydney Grove, a lay-by, a side street — and leave the vehicle there. Lasting damage is very rare when a vehicle is stopped soon, and the fuel drain and flush-through that still come first take care of it.
What The Burroughs motorists get told about petrol in a diesel — and the myths in it
Myth: topping up to full with diesel makes it fine. It doesn't. Topping up removes nothing; it gives you a bigger tank of the same mixture. That guidance supposes a diesel fuel system handles petrol by percentage. It does not.
Not so: a modern diesel copes with a bit of petrol. If anything, the opposite. Protection counts more on current diesels, not less, since their fuel runs through smaller components at higher pressure.
This is the one that fools people. Myth: "If it starts and drives, there's no damage done." Any petrol motor fed diesel generally will not run, and so the motorist stops and the harm stops with them. Nothing seems to have happened when a diesel fed petrol fires up, ticks over and drives away, as it usually does; meanwhile your pump wears. A running engine does not mean fine.
An outdated workaround for a separate problem is behind this one. Myth: "Add some two-stroke oil and drive the vehicle home." It doesn't put back what petrol has diluted, and that petrol is still inside your tank later on.
Myth: "Drain your tank yourself and you are sorted." Once the motor has been run, some of the petrol is no longer in your tank: it is in the fuel filter and the lines, and it goes straight back through the pump on your next start. On top of that, petrol emptied into a can by the road is genuinely hazardous.
Petrol in a diesel: how does it occur?
On purpose? Never. Through carelessness? Rarely, if ever. One way only, because of the nozzles: the slimmer petrol one slips inside a diesel filler with almost no resistance, whereas the diesel one mostly won't fit a petrol car. That's how the forecourt makes it easy.
When habit and your car stop matching, it takes place. Any vehicle that's new to you — hired, on loan as a courtesy car, or just bought. A household with one petrol and one diesel on the drive. A forecourt you know, only with its pumps laid out differently. Racing for a train at Hendon and fuelling up en route. Years of petrol motors behind you, a diesel Renault Megane in front of you on the forecourt for its first tank — that's when. Your hand repeats what it has always done once you add rain, a phone call or a back seat full of kids.
Avoiding petrol in a diesel next time you fill up in The Burroughs
- The label is what matters, and so check the petrol pump rather than the colour: in the UK unleaded handles are usually green and diesel black, but not on each forecourt.
- Inspect your filler flap. Many vehicles state the fuel type inside the flap or on the cap. Look at it on your first fill in any car you do not know.
- One of each in the home? Label the key to your diesel — a coloured fob, a sticker — since meaning to remember isn't enough.
- Before the nozzle comes off the petrol pump the first time you fill a hired or new vehicle, say "diesel" out loud. Silly, perhaps, but it works.
- While you're thinking about something else, this is an easy mistake to make — so put your phone away.
- Up to a point, a misfuel inhibitor helps: some diesels come with a filler built to refuse a petrol nozzle, and add-on devices exist for the remainder. Treat it as a safety net, then keep reading the pump.
- Less petrol makes a thinner mix, so stop the moment you notice — though remembering that your next step is unchanged. It is still not to fire it up.
Already put petrol in a diesel in The Burroughs?
Then the order of things is brief. Leave it unstarted, with the ignition off as well. Ask the attendants to help you push it away from the petrol pump if you're still on the forecourt, whether that is Esso or anywhere else. Next, 0333 366 0103. We will ask what went in, roughly how much, and if it has been run.
Corrosion and deposits are the trouble with AdBlue, whereas petrol means lost protection. So if it was AdBlue, say so — and read its own The Burroughs page.
One petrol in a diesel task around The Burroughs costs more than another. Why?
An honest single price does not exist here: four scenarios, four separate tasks. The scenario itself does most of the work of moving the cost. Where the car is counts too, and whether a van can safely reach it, after the ratio of petrol to what your tank takes.
Before any quote, not after, we ask three questions: your fuel that went in, its amount, and if it's run. That's why. With those replies, there is a straight figure rather than a range.
About The Burroughs and its setting
The Burroughs is a suburban area in northwest London, situated approximately 6.7 miles from the city centre. The Burroughs has a relatively low elevation of 67 metres and is surrounded by nearby places such as Hendon, Brent Cross, and West Hendon. The Burroughs is predominantly composed of flat-type housing, which is typical of many London suburban areas. The Burroughs is close to major urban hubs, including Westminster, which is about 7.1 miles away.
Across Greater London and around The Burroughs: fuel drain cover
Petrol in diesel calls around The Burroughs — part of the NW postcode area — go to vans that likewise cover the places around it, Hendon, Brent Cross and West Hendon included. A forecourt, a supermarket car park, a lay-by or your own driveway are all places we work, and your car does not need to come to us.
At the pump in The Burroughs, still?
In that case, you could not be in a better spot. Call, and leave it switched off.