How Worried Should You Be? Petrol in a Diesel Car in Swanscombe
Far less than you likely are, provided it hasn't been started. "Have I ruined it?" is the first question anyone in Swanscombe asks, and the honest answer is normally no, because petrol resting in a diesel tank hurts nothing until it's drawn through your fuel system — by ignition priming, by your starter, or by being driven. Petrol in Diesel is who to ring, with your engine kept off, and so it stays that way. What petrol really does to a diesel, how to gauge how far it's travelled, and how to keep it from happening again: that's the remainder of this page.
Your engine and petrol in a diesel: what goes on
On its way through an engine, diesel has two tasks. It protects to begin with, and after that does it burn. Designed to very fine gaps, the injectors and your pump rely on your diesel flowing through them to stop their surfaces wearing against one another.
Petrol does the first job poorly and the second not at all. The rattling comes from petrol being made not to ignite when compressed, which is exactly the opposite of what a diesel needs. On top of that it is runnier than diesel, it strips away the lubrication the system depends on, and any pump running on that mixture is wearing itself.
The shape of the trouble is plain once you put those together. Contact doesn't do the harm — circulation does. Where the petrol is only inside your tank, it is a fault of fuel, nothing more. After your pump has been running on that petrol, a mechanical issue has started: whatever is shed by a pump that's wearing down is carried downstream to the fuel injectors with your fuel.
Four situations our engineers see in Swanscombe: how serious is petrol in a diesel?
The best case there is: filled up, not once started. At a forecourt, and really only there, that petrol is still confined to your tank — since anywhere else the car was driven to reach it. The job is draining and purging on the spot.
A brief spell of running, or just the ignition on. Petrol has left that tank and reached the filter and your lines, because the fuel system has been primed. Normally little more than clearing, flushing and sorting your filter, so still straightforward.
A few miles driven, and your pump has spent each of them working on weakened fuel. Distance is only half of it; how hard it was driven matters just as much. Either way the work runs to the tank, your lines, your filter and fresh fuel through the whole system. Short trips, like the school run to Knockhall Primary School, are one matter. A run as far as London, under 25 miles away, is a very different task. So is any distance on the M25, under 3 miles from Swanscombe, where the motor has been working hard the whole time.
Driven until it protested. Clattering, a ragged idle, smoke, a throttle that has gone soft. The motor is telling you your fuel is no longer acting like diesel. Leave it where it has stopped: a lay-by, a side street, the verge on High Street. The fuel drain and flush still come first, and they deal with it: if a vehicle is stopped quickly, permanent damage is very rare.
Petrol in a diesel stories Swanscombe motorists hear
It will not be fine. The myth: "Fill it the rest of the way with diesel and it will be." A bigger tank of the same mixture is all you get, since topping up takes out nothing. That guidance supposes a diesel fuel system handles petrol by percentage. It doesn't.
"Modern diesels can handle a little petrol" — a myth, and nearer the reverse. At higher pressure, through finer parts: that is how a modern diesel moves its fuel, and so the lubrication counts more, not less.
Myth: "If it starts and drives, there is no harm done." This is the one that catches motorists. Feed diesel to a petrol motor and it normally will not run, so the motorist stops — and the harm stops with them. Nothing seems to have happened when a diesel fed petrol fires up, ticks over and drives away, which it usually does; meanwhile the pump wears. Fine and running aren't the same at all.
Myth: "Add some two-stroke oil and drive the car home." It's an old workaround for a separate problem. It does not put back what petrol has diluted, and the petrol is still inside the tank later on.
If your engine has been run, part of that petrol is in the filter and your lines, not that tank — and the next start pulls it right back through your pump. So the myth "drain that tank yourself and you're sorted" does not stand up. And, a can of petrol filled by the kerbside is genuinely dangerous.
How does petrol in a diesel happen?
It is rarely carelessness, and no one does it on purpose. One way only, since of the nozzles: the narrower petrol one slips inside a diesel filler with almost no resistance, whereas the diesel one mostly won't fit a petrol car. That's how the forecourt makes it easy.
When habit and the car stop matching, it takes place. Any motor that's new to you — a hire car, on loan as a courtesy car, or just bought. Two cars on one drive, one petrol, one diesel. The pumps in a different order on a well-known forecourt. Racing for a train at Greenhithe for Bluewater and fuelling up en route. The first fill-up in a diesel Renault Clio after years of driving petrol is precisely the moment it takes place. The hand repeats what it has always done once you add rain, a phone call or a back seat full of kids.
Avoiding petrol in a diesel next time you fill up around Swanscombe
- Not every forecourt in the UK keeps to green for unleaded and black for diesel, though most usually do. Check the petrol pump's label; the colour is only a hint.
- In a motor you don't know, look inside the flap over your filler or at the cap before your first fill: many motors state the fuel there.
- Mark your key. In a household with one of each, a coloured fob or a sticker on the diesel's key does more than any amount of intending to remember.
- It seems daft 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 petrol pump.
- Tuck your phone away. This is an easy mistake to make whilst you are thinking about something else.
- Add-on devices exist for cars without one, and some diesels are built with a filler that will not accept a petrol nozzle. Helpful — but a backstop only, never a reason to stop checking the label.
- As soon as you notice, stop: less petrol in the tank makes a thinner blend. What to do next doesn't change, though — still don't start the car.
Put petrol in a diesel in Swanscombe already?
Then the order of things is short. Don't switch your ignition on, and don't fire it up. If you are still at the forecourt — Esso or anywhere else — ask the attendants to help you roll the vehicle clear of the pump. What went in, about how much, and if it's run: tell us those when you ring 0333 366 0103.
If it was AdBlue instead of petrol, say so. That is a different issue — corrosion and deposits instead of lost lubrication — and it has its own page for Swanscombe.
One petrol in a diesel job around Swanscombe costs more than another. Why?
The four situations above are four different tasks, so no single price for this would be honest. The scenario itself does most of the work of moving your cost. Where the vehicle is matters too, and whether a van can safely get to it, after the share of petrol to what your tank takes.
Three queries come first, before quoting, rather than after — what went in, how much, has it run — and that is the reason. Given those replies, there is a straight figure instead of a range.
About Swanscombe and its setting
Swanscombe is a town situated on the southern bank of the River Thames in Kent, with a low elevation of around 10 metres above sea level. Swanscombe is located near the towns of Greenhithe and Stone, and is close to the M25 motorway. Swanscombe has a high proportion of flat housing and is approximately 18 miles from central London. Swanscombe is part of the wider Dartford urban area, with nearby villages including Knockhall.
Fuel drain cover across Kent, Swanscombe included
Swanscombe rests in the DA postcode area, and the vans that answer petrol in diesel jobs there work the spots near it as well — Greenhithe, Knockhall and Stone among them. The car doesn't need to move to us: our engineers drain on a forecourt, in a supermarket car park, in a lay-by or on your own driveway.
In Swanscombe and still at the pump?
In that case, you couldn't be in a better position. Ring, and keep it turned off.