Petrol in a Diesel Car in Wildridings: How Worried Should You Be?
Not started? Then less anxious than you likely are. Petrol sitting in a diesel tank does nothing to the motor till something draws it through your fuel system — your ignition priming your pump, the starter, or the drive on its own. So the fair answer to the first question everyone in Wildridings asks, "have I ruined it?", is normally no. To leave the vehicle that way, phone Petrol in Diesel and leave the engine alone. What petrol really does to a diesel, how to gauge how far it has gone, and how to keep it from happening a second time: that is the rest of this page.
Petrol in a diesel: what does it do to the engine?
Passing through an engine, diesel is doing two things at once. It protects to begin with, and only then does it burn. Extremely fine clearances go into your injectors and your high-pressure pump, and only the diesel flowing through stops those surfaces grinding together.
The second job petrol does not do at all, and the first it does badly. A pump running on a petrol mixture is wearing itself out, because petrol is thinner than diesel and strips out the protection the fuel system depends on. Petrol is also designed to resist igniting under compression — the opposite of what a diesel needs from its fuel — and that is where the clattering comes.
Combined, those leave the shape of the trouble clear. Contact doesn't do the damage — circulation does. A tank with petrol in it is a fuel issue. Once the pump has been working on that petrol, a mechanical issue has begun: anything shed by a pump that's wearing down travels onward to the fuel injectors with your fuel.
Four situations our engineers see in Wildridings: how bad is petrol in a diesel?
Fuelled but never started — the best it gets. On a forecourt, and really only there, the petrol is still limited to the tank — because everywhere else the vehicle was driven to get to it. The job is emptying and rinsing on the spot.
A brief spell of running, or merely the ignition on. The system has been primed, so petrol has left your tank and got to your filter and your lines. That is usually still a simple task — a drain, a flush, and your filter dealt with.
Driven a few miles. Now the pump has spent those miles running on weakened fuel. The work is that tank, the fuel lines, the fuel filter and clean fuel through the entire circuit, and how hard the vehicle was driven matters as much as how far. Short trips, like the school run to Wildridings Primary School, are one matter. Driving as far as Westminster, under 50 miles away, makes a very different job — as does any distance on the A329(M), under 3 miles from Wildridings, with the motor running hard the whole time.
Driven until it complained. Rattling, a lumpy idle, smoke, a throttle that has gone soft. The motor is telling you the fuel is no longer acting like diesel. Stop where you are — on the verge on Netherton, at the kerb, down a side road — and do not move it. The fuel drain and flush still go first, and they take care of it: if a car is stopped soon, lasting damage is very uncommon.
Petrol in a diesel myths Wildridings people hear
Myth: "Fill it the rest of the way with diesel and it will be fine." It will not. Nothing is removed by topping up — you are left with a fuller tank, still the same mix. A diesel fuel system doesn't tolerate petrol by percentage in the way that advice supposes.
If anything, the reverse is true. Myth: "A modern diesel can cope with a bit of petrol." At higher pressure, through more precise parts: that's how a newer diesel moves its fuel, so the lubrication matters more, not less.
Myth: "If it starts and drives, there's no damage done." This is the one that catches drivers. Feed diesel to a petrol motor and it generally won't run, so the driver stops — and the damage stops with them. Whilst your pump grinds, a diesel fed petrol normally starts, ticks over and drives away as though nothing has happened. A running engine does not mean fine.
An old fix for a separate fault lies behind this one. Myth: "Add some two-stroke oil and drive the car home." None of what petrol weakened is put back by it — and later, the tank still contains the petrol.
"Drain it yourself and you're sorted" — a myth, because after it's been running some petrol sits in your filter and lines, ready to go straight back through your pump on the next start. Besides, petrol cleared into a can by the road is genuinely dangerous.
How it happens: petrol in a diesel
On purpose? Never. Through carelessness? Rarely, if ever. A diesel nozzle mostly won't go into a petrol motor, but the smaller petrol nozzle goes into the filler of a diesel nearly without resistance — so forecourts make this one error straightforward, and just in that direction.
When habit and your car stop matching, it takes place. Courtesy car, hire car, or a vehicle that's brand new. Households running one of each, petrol and diesel. Your usual forecourt, its pumps suddenly in a different order. A train to catch, and a rushed fill on the way to Bracknell. A new-to-you diesel Renault Megane, its first fuelling, and a driver accustomed to petrol: exactly when it happens. Add rain, a phone call or a back seat full of kids, and your hand does what it has always done.
Avoiding petrol in a diesel next time you fill up in Wildridings
- The label is what matters, and so check the pump rather than the colour: in the UK unleaded handles are normally green and diesel black, yet not on each forecourt.
- In a motor you do not know, look inside the flap over your filler or at the cap before your first fill: many cars print the fuel there.
- A coloured fob or a sticker on your diesel's key does more than any amount of meaning to remember, for a house with one of each.
- It sounds silly and it does the trick: on your first fill in a new or hired car, say "diesel" out loud before you lift the nozzle off the pump.
- Thinking about something else is when this becomes an easy mistake to make, and so put the phone away and keep your mind on the petrol pump.
- A misfuel inhibitor helps, up to a point. Some diesels have a filler built to block a petrol nozzle, and add-on devices are available for cars without one. They are a backstop, not a reason to stop reading the pump.
- As soon as you notice, stop: less petrol inside your tank means a thinner mixture. What to do next does not change, though — still don't fire it up.
Already put petrol in a diesel in Wildridings?
The order of things is short, then. Leave it unstarted, with your ignition switched off too. The staff on the forecourt — whether at Shell itself or wherever you filled up — will normally help push it clear of the pump if you ask. What was put in, roughly how much, and whether it has run: tell us those when you ring 0333 366 0103.
If it was AdBlue rather than petrol, say so. That is a separate fault — corrosion and deposits rather than lost lubrication — and it has its own page for Wildridings.
What makes one Wildridings petrol in a diesel job cost more than the next
There's no honest single quote for this, because the four situations above are four separate jobs. Which of them you're in is chiefly what shifts the cost. Where the vehicle is matters too, and whether a technician can safely get to it, after the ratio of petrol to what the tank takes.
Before any quote, not after, we ask three queries: the fuel that was put in, its volume, and whether it has run. That is why. Their replies are what turn a range into one firm number.
About Wildridings, briefly
Wildridings is a suburban area in Berkshire, situated approximately 28 miles west of London and near the town of Bracknell. Wildridings lies at an elevation of around 80 metres, in a gently undulating landscape of inland southern England. Wildridings is characterised by its predominantly terraced housing stock, with nearby neighbourhoods including Easthampstead and Skimpedhill.
Fuel drain cover around Wildridings and across Berkshire
Petrol in diesel jobs around Wildridings — part of the RG postcode area — go to vans that also cover the spots around it, Easthampstead, Skimpedhill and Bracknell included. The vehicle does not need to move to us: we drain at a forecourt, in a supermarket car park, in a lay-by or on your own drive.
In Wildridings and still at the pump?
No position is better: that's where you now are. Call, and leave it switched off.