Park Barn: Petrol in a Diesel Car? How Worried to Be
Likely less than you already are — as long as no one has started the vehicle. Till the ignition primes your pump, your starter cranks, or your vehicle is driven, petrol in a diesel tank simply sits there and does nothing. Which makes the truthful reply to that first Park Barn query — "have I ruined it?" — normally no. To leave the car that way, ring Petrol in Diesel and leave your engine alone. The rest of this page sets out 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.
Your engine and petrol in a diesel: what happens
Passing through an engine, diesel is doing two things at once. Before it burns, it lubricates — then it ignites. Your high-pressure pump and your injectors are designed to very fine clearances, and your diesel passing through them is what keeps those surfaces from grinding against one another.
Poorly at the first, not at all at the second: that is petrol. The rattling comes from petrol being designed not to ignite when compressed, which is precisely the reverse of what a diesel needs. On top of that it is runnier than diesel, it strips out the protection your system depends on, and any pump working on such a mixture is wearing itself.
Taken together, they show the shape the trouble takes. The harm is done by movement, not by contact. All a tank with petrol in it amounts to is a fuel problem. The start of a mechanical problem is a pump that has been running on that petrol — and whatever a worn pump sheds moves on with your fuel to your injectors beyond it.
Petrol in a diesel around Park Barn: how serious is it? Four cases
Filled but never started — as good as it gets. Only the tank has petrol in it, and so the task is draining that tank and cleaning your system where the car stands. This scenario can only truly occur at a forecourt: anywhere else, your car got there by being driven.
The ignition switched on, or a brief start. With the fuel system primed, your lines and filter already hold petrol that came from that tank. Still normally simple: drain, flush, and the fuel filter sorted.
The pump now spent a few miles on diluted fuel — that is what driving the vehicle meant. Distance is only half of it; how hard it was driven counts just as much. Either way the work includes your tank, the fuel lines, the filter and clean fuel through the whole circuit. Driving the children to Guildford Grove Primary School is one sort of trip. Any mileage on the M3, under 10 miles from Park Barn, means your engine working hard throughout, and a run to Westminster, under 50 miles away, makes a very different job too.
Driven till it complained. Rattling, a lumpy idle, smoke, a throttle that has gone soft. That is your engine telling you its fuel has stopped behaving like diesel. Pull up wherever you are — the verge on Southway, a lay-by, a side street — then leave it where it is. A car pulled over early very rarely has permanent damage, because the fuel drain and the flush-through, which still come first, sort it out.
What Park Barn motorists get told about petrol in a diesel — and the myths in it
False: 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 mix. Percentage is not how a diesel fuel system tolerates petrol, whatever that advice assumes.
"Current diesels can handle a little petrol" — a myth, and nearer the opposite. A newer diesel sends its fuel through finer parts at higher pressure, which makes the lubrication matter more, not less.
This is the one that fools drivers. Myth: "If it starts and drives, there's no harm done." A petrol motor fed diesel usually will not run, and so the motorist stops and the damage stops with them. Nothing looks to have happened when a diesel fed petrol fires up, ticks over and drives away, as it usually will; meanwhile the pump grinds. Running is not the same as fine.
"A drop of two-stroke oil and drive it home" — a myth, taken from a fix from years ago, for a separate fault. It doesn't put back what petrol has thinned, and the petrol is still in the tank later.
The next start sends petrol back round the pump from the lines and the fuel filter, where some of it ends up once the engine has been run. That's why a DIY tank drain does not sort it — a myth. Emptying petrol into a can at the kerbside is also truly hazardous.
How petrol ends up: petrol in a diesel
Carelessness is seldom the cause, and nobody means to do it. The forecourt makes it simple: the petrol nozzle is the slimmer of the two, and it slips into a diesel filler with almost no resistance, while a diesel nozzle mostly won't go into a petrol motor at all. So the mistake runs one way.
It happens when habit and the vehicle stop matching. Hire cars, courtesy cars, and cars that are new to you. One petrol and one diesel on the drive of the same household. A familiar forecourt with the pumps in a different order. A rushed fill en route to Guildford with a train to catch. A new-to-you diesel Volkswagen Golf, its first fuelling, and a driver accustomed to petrol: exactly when it occurs. Add rain, a phone call or a back seat full of kids, and the hand repeats what it has always done.
Park Barn motorists: how to prevent petrol in a diesel next time
- Not every forecourt in the UK keeps to green for unleaded and black for diesel, though most generally do. Check the pump's label; the colour is only a clue.
- In a motor you do not know, look inside the flap over your filler or at the cap before the first fill: many vehicles print the fuel type there.
- A coloured fob or a sticker on your diesel's key does more than any amount of intending to remember, for a house with one of each.
- It seems daft and it works: on your first fill in a new or hired car, say "diesel" out loud before you take the nozzle off the petrol pump.
- Mistakes like this are simple to make whilst your mind is on something else, so your phone goes away.
- A misfuel inhibitor helps, up to a point. Some diesels come with a filler designed to refuse a petrol nozzle, and add-on devices exist for motors without one. They are a safety net, not a reason to stop reading the pump.
- As soon as you realise, stop: less petrol inside the tank makes a weaker blend. What to do next does not change, though — still do not start the vehicle.
Park Barn: already put petrol in a diesel?
In that case, there is just a short order of things. Don't turn your ignition on, and do not fire it up. The attendants at the forecourt — whether at Esso itself or wherever you filled up — will normally help push it clear of the pump if you ask. What went in, about how much, and if it has run: tell us those when you ring 0333 366 0103.
Say so if it was AdBlue rather than petrol: it's a separate problem, with its own page for Park Barn, since AdBlue brings corrosion and deposits instead of lost lubrication.
One petrol in a diesel job in Park Barn costs more than another. Why?
A fair single quote does not exist here: four situations, four separate tasks. Which of them you're in is chiefly what moves your cost. After that it is the ratio — how much petrol went in against how much the tank holds — and then where your car is and whether a van can get to it safely.
Ahead of any quote, not after, we ask three queries: your fuel that was put in, the volume, and whether it's run. That's why. Given those answers, there is a straight figure rather than a range.
About Park Barn and where it is
Park Barn is a suburban area in Surrey, situated approximately 27 miles southwest of central London. Park Barn sits at an elevation of around 62 metres, near the neighbouring areas of Westborough and Rydeshill. Park Barn is characterized by its predominantly semi-detached housing stock, reflecting the typical residential development patterns of the South East region. Park Barn remains a relatively small, yet distinct, community within the wider Surrey area.
Fuel drain cover in Park Barn and across Surrey
Westborough, Dennisville and Rydeshill are among the locations near Park Barn that the same teams work, answering petrol in diesel call-outs across Park Barn's GU postcode area. No need to bring your vehicle to us. Forecourts, supermarket car parks, lay-bys and your own driveway are all places where we work.
Park Barn: still at the petrol pump?
No position is better: that is where you are. Keep the car switched off, then ring.