Stanway: Petrol in a Diesel Car? How Worried to Be
Probably less than you are now — provided no one has started the car. Petrol resting in a diesel tank does nothing to the motor until something pulls it through your fuel system — your ignition priming the pump, your starter, or the drive on its own. So the truthful answer to the first question anyone in Stanway asks, "have I wrecked it?", is normally no. Petrol in Diesel is who to ring, with your motor kept off, so it remains that way. Below, you will find what petrol actually does inside a diesel, how far it may have got, and how to stop it happening to you a second time.
Petrol in a diesel: what does it do to your engine?
On its way through an engine, diesel does two jobs. It combusts, and before it combusts it protects. What stops the surfaces inside the high-pressure fuel pump and the injectors from grinding against one another is the diesel passing through them — they are made to very fine tolerances.
Of those two tasks, petrol handles the first badly and the second never. 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 lubrication the system hinges on, and any pump working on that mixture is wearing itself.
Combined, those make the shape of the problem plain. It's circulation that causes the harm, not contact. Where that petrol is only in the tank, it's a problem of fuel, nothing more. The beginning of a mechanical problem is a pump that has been labouring on that petrol — and whatever a worn pump sheds moves on with your fuel to the fuel injectors downstream.
Stanway, petrol in a diesel: four situations, from mild to major
Filled but not once started — the best it gets. The petrol is in that tank and just your tank, and the job is a drain and a flush where the vehicle sits. This is the one scenario that can only really occur on a forecourt, since anywhere else your car has been driven to get there.
Started for a moment, or just the ignition on. With the fuel system primed, the lines and filter now hold petrol that has come from your tank. That is usually still a straightforward job — a drain, a flush, and the fuel filter seen to.
The pump now spent a few miles on diluted fuel — that's what driving it does. How hard the vehicle was driven matters as much as how far, and the work covers the tank, the fuel lines, the filter and fresh fuel through the entire system. Driving the children to Stanway Fiveways Primary School is one kind of trip. A run as far as Colchester, under 3 miles away, is a very different job. So is any distance on the M11, under 50 miles from Stanway, where the engine has been labouring hard the whole time.
It protested, and only then stopped: smoke, rattling, a throttle gone soft, an idle gone uneven. What you are hearing is the motor signalling fuel that no longer runs like diesel. Leave it wherever it stops: a lay-by, a side street, the verge on Threshers End. A vehicle pulled over soon very seldom has lasting damage, since the drain and the flush, which still come first, deal with it.
Myths Stanway motorists hear about petrol in a diesel
Myth: "Fill it the rest of the way with diesel and it'll be fine." It will not. Topping up removes nothing; it gives you a bigger tank of the same mixture. A diesel fuel system does not tolerate petrol by percentage in the way that guidance assumes.
"Modern diesels can handle a little petrol" — a myth, and nearer the reverse. At higher pressure, through smaller components: that is how a modern diesel moves its fuel, so the protection matters more, not less.
This is the one that catches motorists. Myth: "If it starts and drives, there's no harm done." The driver of a petrol engine fed diesel normally has no choice but to stop, since it will not run, and the damage stops with them. While the pump wears, a diesel fed petrol usually starts, idles and drives away as if nothing has happened. Fine and running are not the same thing.
"A drop of two-stroke oil and drive it home" — a myth, taken from a fix from years ago, for a separate fault. None of what petrol diluted is put back by it — and afterwards, your tank still holds that petrol.
The next start draws petrol back round your pump from the lines and your filter, where some of that sits after the engine has been run. That's why draining the tank yourself does not sort it — a myth. Emptying petrol into a can by the kerbside is also really dangerous.
Petrol in a diesel: how does it take place?
It is rarely carelessness, and no one does it on purpose. The petrol nozzle is the smaller of the two and slides into a diesel filler with almost no resistance; a diesel nozzle mostly will not go into a petrol vehicle at all. The forecourt makes it easy, and the slip runs one way.
It happens when habit and the vehicle stop matching. A vehicle that is new to you — hired, on loan as a courtesy car, or brand new. Two vehicles on one drive, one petrol, one diesel. Your normal forecourt, its pumps suddenly in a different order. Racing for a train at Marks Tey and fuelling up en route. Exactly the moment it occurs: after years of driving petrol, a driver fills a diesel Renault Megane for the first time. With rain, a call arriving, or a car full of children to deal with, the hand just does what it always has.
Avoiding petrol in a diesel next time you fill up around Stanway
- Green for unleaded and black for diesel is normal in the UK — but not on every forecourt. Go by the label on the pump, not the colour.
- Plenty of motors state the fuel inside your filler flap or on the cap, so check it on your first fill in any motor you don't know.
- Good intentions count for less than a sticker or a fob in a bright colour on the diesel's key when a household has one of each. So mark it.
- It sounds 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 pump.
- Thinking about something else is when this becomes an easy mistake to make, and so put your phone away and keep your mind on the petrol pump.
- A misfuel inhibitor helps, up to a point. Some diesels have a filler designed to block a petrol nozzle, and add-on devices are available for vehicles without one. They are a backstop, not a reason to stop checking the petrol pump.
- The moment you realise, stop: less petrol inside the tank means a thinner mixture. What to do next doesn't change, though — still do not crank it.
Stanway: already put petrol in a diesel?
The order of things is short, then. Leave it unstarted, with your ignition off too. The attendants at the forecourt — whether at East of England Coop itself or wherever you filled up — will usually help push it away from the pump if you ask. Then phone 0333 366 0103 and tell us what was put in, about how much, and whether it has run.
Corrosion and deposits are the issue with AdBlue, whereas petrol brings lost protection. So if it was AdBlue, say so — and see its own Stanway page.
One petrol in a diesel job in Stanway costs more than another. Why?
The four situations above are four different jobs, so no single quote for this would be fair. The scenario itself does most of the work of moving your cost. Two things come after that: the petrol that went in as a proportion of what that tank takes, then the spot the vehicle is in and whether a van can reach it safely.
What was put in, how much, and if it has run — three questions we ask before costing, not after, for precisely that reason. With the replies, there is a straight figure rather than a range.
About Stanway and its setting
Stanway is a suburban area located near Colchester in Essex, sitting at an elevation of 43 metres in the gently rolling inland landscape. Stanway is characterized by its predominantly semi-detached housing stock and is situated close to nearby places such as Beacon End and Lexden. Stanway is also within commuting distance of London, being approximately 48.9 miles from the capital. Stanway remains a residential community on the outskirts of Colchester, with Chitts Hills nearby.
Stanway and Essex: where our fuel drain cover runs
Beacon End, Chitts Hills and Lexden are among the spots around Stanway that the same vans work, answering petrol in diesel call-outs across Stanway's CO postcode area. A forecourt, a supermarket car park, a lay-by or your own driveway are all spots we work, and your car does not need to move to us.
Still at the pump in Stanway?
The best spot there is, then — that's where you are. Keep it off. Phone.