How Worried Should You Be? Petrol in a Diesel Car in The Quay
If it has not been started, you can worry less than you probably are. Until your ignition primes the pump, the starter cranks, or the vehicle is driven, petrol in a diesel tank just rests there and does no harm. Which means the honest reply to the first The Quay question — "have I ruined it?" — usually no. Keep it that way: leave the motor off then ring Petrol in Diesel. The rest of this page covers what petrol really does to a diesel, how to tell how far it has got, and how to make sure it doesn't happen to you again.
Petrol in a diesel: what does it do to the engine?
Diesel does two jobs on its way through a motor. It combusts, and before it combusts it protects. Your high-pressure pump and your injectors are made to very fine tolerances, and the diesel passing through them is what keeps those surfaces from wearing down against each other.
The second task petrol doesn't do at all, and the first it does poorly. The knocking 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 thinner than diesel, it strips away the lubrication your system hinges on, and any pump working on that mix is wearing itself.
Together, those make the shape of the trouble plain. Contact doesn't do the damage — circulation does. Where that petrol is only inside the tank, it is a fault of fuel, nothing more. A pump that has been labouring on that petrol is the start of a mechanical one, and whatever a worn pump sheds travels on with your fuel to the fuel injectors downstream.
Four scenarios our engineers see in The Quay: how bad is petrol in a diesel?
The best case there can be: filled up, not once started. Being at a forecourt is what makes this possible: elsewhere, the vehicle has been driven there to begin with. With that petrol kept inside the tank alone, it's emptied and rinsed right where it stands, and nothing more is needed.
Started for a moment, or only your ignition on. Once primed, the system has drawn petrol out of the tank as far as the fuel filter and the fuel lines. Usually nothing more than clearing, cleaning and sorting the filter, and so still easy.
Driven a few miles. Now the pump has spent these miles labouring on thinned fuel. Tank, lines, filter, then clean fuel put through the entire system: that's the work, and the way your car was driven matters as much as the miles. Short trips, such as the school run to St Leonard's (CofE) Primary School (VC), are one matter. Any mileage on the M5, under 3 miles from The Quay, means the engine has worked hard throughout, and a run to Exeter, under a mile away, is a very different job as well.
Driven on until it complained — clattering, smoke, an uneven idle, a dead throttle. That is your motor telling you its fuel has stopped acting like diesel. Whether it is the verge on Watergate, a lay-by or a side street, stop where you are and leave it. A car stopped soon very rarely has permanent damage, as the fuel drain and the flush, which still come first, sort it out.
Petrol in a diesel myths The Quay motorists hear
It will not be fine. The myth: "Fill it the rest of the way with diesel and it will be." A fuller tank of the same mixture is all it gives, since topping up removes nothing. The idea behind that advice — that diesel fuel systems tolerate petrol by percentage — is wrong.
"Newer diesels can handle a little petrol" — a myth, and nearer the reverse. A modern diesel sends its fuel through finer parts at higher pressure, which makes the lubrication count more, not less.
The myth that catches motorists off guard: if it starts and drives, it must be unharmed. Diesel in a petrol motor normally leaves a motor that won't run: the motorist stops, and so does the damage. Nothing looks to have happened when a diesel fed petrol fires up, ticks over and drives away, as it usually does; meanwhile the pump grinds. Running does not mean fine.
"A drop of two-stroke oil and drive it home" — a myth, borrowed from a fix from years ago, for a different fault. None of what petrol thinned gets put back by it — and afterwards, the tank still holds the petrol.
Myth: "Drain that tank yourself and you are sorted." After the motor has run, some of that petrol is no longer in the tank: it's in your filter and your lines, and it goes straight back through the pump on the next start. It is also truly hazardous to drain petrol into a can by the kerbside.
Why petrol in a diesel takes place at all
A careless moment is seldom the cause, and no one means to do it. A diesel nozzle generally will not 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 error easy, and just in one direction.
It occurs when habit and the car stop matching. Hire cars, courtesy cars, and vehicles that are new to you. Households running one of each, petrol and diesel. A forecourt you know, only with its pumps laid out differently. A train to catch, and a hurried fill en route to Exeter St Thomas. Years of petrol cars behind you, a diesel Volkswagen Golf in front of you at the forecourt for its first tank — that is when. Throw in a back seat full of kids, a phone call or rain, and habit takes over.
Next time you fill up in The Quay: avoiding petrol in a diesel
- The label is what counts, so read the pump instead of the colour: in the UK unleaded handles are normally green and diesel black, but not on every forecourt.
- In a vehicle you do not know, look inside the flap over the filler or at the cap before the first fill: plenty of motors state the fuel there.
- Good intentions count for less than a sticker or a fob in a vivid colour on the diesel's key when a house has one of each. So mark it.
- It seems daft and it does the trick: on your first fill in a new or hired car, say "diesel" aloud before you take the nozzle off the pump.
- Thinking about something else is when this becomes an easy mistake to make, so put the phone away then keep your mind on the pump.
- Some diesels have a filler designed to refuse a petrol nozzle, and devices you can add exist for vehicles without one. Such an inhibitor helps up to a point — as a safety net, not a reason to stop reading the petrol pump.
- The moment you notice, stop: less petrol in the tank means a thinner mixture. What to do next doesn't change, though — still don't fire it up.
Petrol already in a diesel in The Quay? Start here
The order of things is brief, then. Starting it is out, and so is turning on your ignition. Still on the forecourt, at Esso or anywhere else? Ask the attendants to help you roll it clear of the pump. Next, 0333 366 0103. We'll ask what got in, about how much, and if it has been run.
AdBlue, not petrol? Then tell us. Corrosion and deposits, not lost protection, make it a separate issue — The Quay has a page just for it.
The Quay petrol in a diesel tasks: why one costs more than another
The four situations above are four different tasks, so no single price for this would be honest. Which of them you're in is chiefly what shifts the cost. The share matters next, meaning how much of that tank is petrol, followed by the position of the car and whether getting to it is safe for a van.
Ahead of any quote, not after, come three queries: your fuel that got in, the volume, and if it's run. That's why. The answers turn a range into a straight figure.
About The Quay
The Quay is a suburban area located on the riverside in Devon, with a mix of residential and commercial properties. The Quay sits at an elevation of 44 metres, close to the city centre of Exeter, and is characterized by a high proportion of flat dwellings. The Quay is part of the larger Exeter urban area, with nearby neighbourhoods including Barnfield and St Leonards. The Quay has a population of approximately 8793 residents, making it a sizable suburban community.
Across Devon and around The Quay: fuel drain cover
The vans answering petrol in diesel jobs in The Quay, in the EX postcode area, equally work the places near it, Exeter, Barnfield and St Leonards among them. No need to move the car to us. Forecourts, supermarket car parks, lay-bys and your own driveway are all places where we work.
Still at the petrol pump around The Quay?
No position is better: that's where you now are. Keep it off. Phone.