Bolbeck Park: Petrol in a Diesel Car? How Worried to Be
Less than you likely are, provided it has not been started. Everyone around Bolbeck Park begins with "have I ruined it?", and the fair answer is generally no: petrol resting in the tank of a diesel stays harmless until priming, cranking or driving draws it into the system. To leave the car like that, phone Petrol in Diesel and leave the engine alone. What petrol really does to a diesel, how to gauge how far it has travelled, and how to keep it from happening a second time: that's the remainder of this page.
Petrol in a diesel: what does it do to your engine?
Passing through a motor, diesel does two things at once. Oiling comes before burning; it does both. The high-pressure pump and the fuel injectors are built to very fine tolerances, and the diesel passing through them is what keeps those surfaces from wearing against each other.
The second job petrol doesn't do at all, and the first it does poorly. It's runnier than diesel and strips away the protection the fuel system depends on, and so a pump running on a petrol blend is a pump wearing itself. And petrol is made to resist igniting under compression, which is the opposite of what a diesel needs from its fuel. That is where the knocking comes from.
Put those together and the shape of the problem is plain. It's circulation that causes the harm, not contact. Any tank with petrol in it is a fuel problem. After the pump has been working on that petrol, a mechanical fault has begun: whatever is shed by a pump that's grinding travels downstream to the fuel injectors with the fuel.
Four scenarios our technicians see around Bolbeck Park: how bad is petrol in a diesel?
Filled up, never started. The best case there is. Just the tank has petrol in it, so the task is clearing that tank and purging your system where the vehicle sits. This scenario can only really occur on a forecourt: anywhere else, the vehicle got there by being driven.
A moment's running, or merely your ignition on. The system has been primed, and so petrol has left that tank and got to your filter and the lines. That is generally still a simple task — a drain, a flush, and your filter seen to.
A couple of miles driven, and your pump has spent each of them working on weakened fuel. How hard the car was driven counts as much as how far, and this work takes in your tank, the fuel lines, the filter and clean fuel through the whole system. The school run to Willen Primary School is one matter. Very different once more: a run to Milton Keynes, under 3 miles away, or any distance on the M1, under a mile from Bolbeck Park, where the motor kept working hard.
Driven until it complained. Knocking, an uneven idle, smoke, a throttle that has gone soft. What you are hearing is the engine signalling fuel that no longer acts like diesel. Stop wherever you are — the verge on V10 Brickhill Street, a lay-by, a side street — then leave the car where it is. Lasting damage is very rare if a car is pulled over early, and the fuel drain and flush that still go first deal with it.
Bolbeck Park motorists and that petrol in a diesel myths they hear
False: topping up to full with diesel makes it fine. It does not. Nothing is removed by topping up — you are left with a fuller tank, still the same mixture. The idea behind that guidance — that diesel fuel systems tolerate petrol by percentage — is wrong.
Myth: "A current diesel can cope with a bit of petrol." If anything, the reverse. Smaller components and higher pressure are how a current diesel runs its fuel, and that makes the lubrication matter more, not less.
"It starts, it drives, and so no harm done" — the myth that catches more motorists than any other. Feed diesel to a petrol engine and it usually won't run, and so the driver stops — and the damage stops with them. Feed petrol to a diesel and it generally starts, idles and drives away as if nothing has happened — all while its pump is wearing. Fine and running aren't the same thing.
Myth: "Add some two-stroke oil and drive the car home." It's an outdated fix for a different fault. What petrol has diluted remains diluted, and the petrol stays inside that tank regardless.
Myth: "Drain that tank yourself and you're sorted." After the motor has run, some of the petrol is no longer inside the tank: it is in the fuel filter and the fuel lines, and it goes right back through your pump on your next start. Also, a can of petrol filled at the roadside is genuinely hazardous.
How petrol ends up: petrol in a diesel
Nobody does it on purpose, and it's seldom carelessness. A diesel nozzle generally won't go into a petrol motor, but the slimmer petrol nozzle goes into the filler of a diesel nearly without resistance — so forecourts make this one mistake straightforward, and only in that direction.
It happens when habit and the vehicle stop matching. Hire cars, courtesy cars, and vehicles that are new to you. A household with one petrol and one diesel on the driveway. A forecourt you know, only with its pumps laid out differently. A rushed fill en route to Milton Keynes Central with a train to catch. The first fill-up in a diesel Volkswagen Passat after years of driving petrol is exactly the moment it occurs. With rain, a call coming in, or a car full of children to deal with, your hand simply does what it always has.
Bolbeck Park people: how to prevent petrol in a diesel next time
- A green handle for unleaded and black for diesel is normal in the UK — but not on each forecourt. Go by the label on the pump, not the colour.
- The first fill in a strange vehicle is the time to check your filler flap — inside it, or on the cap, many cars state the fuel they take.
- Good intentions count for less than a sticker or a fob in a vivid colour on the diesel's key when a household has one of each. So mark it.
- "Diesel", out loud, before you lift the nozzle — every time a new or hired car needs its first tank. It seems daft. It does the trick.
- Put the phone away. This is an easy mistake to make whilst you're thinking about something else.
- A misfuel inhibitor helps, up to a point. Some diesels have a filler designed to reject a petrol nozzle, and add-on devices are available for vehicles without one. They are a safety net, not a reason to stop checking the petrol pump.
- Spotting it mid-fill? Stop there and then. A thinner blend follows from less petrol in that tank, but your next stage stays the same: don't start the car.
Bolbeck Park: already put petrol in a diesel?
The order of things is short, then. Leave it unstarted, with your ignition switched off too. If you're still on the forecourt — Esso or anywhere else — ask the attendants to help you push the car away from the pump. Next, 0333 366 0103. We will ask what went in, about how much, and if it has been run.
If it was AdBlue instead of petrol, say so. That's a separate issue — corrosion and deposits rather than lost lubrication — and it has its own page for Bolbeck Park.
One petrol in a diesel task in Bolbeck Park costs more than another. Why?
The four situations above are four different jobs, so no single price for this would be honest. What moves your cost is mostly which of them you're in. Two things come after that: the petrol that got in as a proportion of what that tank holds, then the place the vehicle is in and whether a technician can get to it safely.
What got in, how much, and whether it's run — three questions our technicians ask before pricing, not after, for precisely that reason. Their replies are what turn a range into one firm number.
About Bolbeck Park and its setting
Bolbeck Park is a suburban area situated on the outskirts of Milton Keynes in Buckinghamshire, with its riverside setting and elevation of around 67 metres. Bolbeck Park lies close to several other residential areas, including Downhead Park and Pennyland, and is approximately 46.5 miles from London. Bolbeck Park is characterised by its predominantly detached housing stock, reflecting the area's residential nature. Bolbeck Park is also near Willen Park, a notable local amenity.
Across Buckinghamshire and around Bolbeck Park: fuel drain cover
Downhead Park, Pennyland and Willen Park are among the places around Bolbeck Park that the same vans work, answering petrol in diesel call-outs across Bolbeck Park's MK postcode area. Our technicians drain wherever your vehicle is — your own driveway, a lay-by, a supermarket car park, a forecourt — so it never needs to come to us.
Still at the pump around Bolbeck Park?
Then you're in the best position there can be. Keep it off. Call.