Habrough: Petrol in a Diesel Car? How Worried to Be
Not started? Then less worried than you likely feel. "Have I ruined it?" is the first question everyone in Habrough asks, and the honest answer is usually no, because petrol resting in a diesel tank harms nothing till it is dragged through the system — by ignition priming, by the starter, or by driving. Leave your engine off and call Petrol in Diesel — that keeps it that way. Further down, you will find what petrol actually does inside a diesel, how far it may have gone, and how to stop it happening to you again.
Inside your engine: what petrol in a diesel really does
On its way through an engine, diesel does two jobs. Oiling comes before burning; it does both. The high-pressure pump and the injectors are made to very fine clearances, and the diesel passing through them is what keeps those surfaces from grinding against one another.
The second job petrol doesn't do at all, and the first it does poorly. It is runnier than diesel and takes away the protection your fuel system depends on, and so a pump running on a petrol blend is a pump wearing itself. And petrol is designed to resist igniting under compression, which is the opposite of what a diesel needs from its fuel. That's where the clattering comes from.
Taken together, they show the shape the trouble has. Not contact but circulation is what does the harm. Where that petrol is only inside your tank, it is a problem of fuel, nothing more. Whatever a worn pump sheds travels on, borne by your fuel, into your injectors further along, which is why a pump that has been working on the petrol is where a mechanical issue starts.
How bad is petrol in a diesel? Four situations our engineers see in Habrough
Filled up, and not started: no case is better. That petrol is in that tank and only the tank, and the job is a drain and a flush where the car sits. This is the one scenario that can only really take place at a forecourt, because anywhere else your car has been driven to get there.
Your ignition turned on, or a brief start. Your system has been bled, so petrol has left the tank and reached the fuel filter and your lines. Still generally simple: drain, flush, and the filter seen to.
Those few miles driven meant your pump labouring on fuel weakened by petrol throughout. Miles is only half of that; how hard it was driven matters just as much. Either way this work runs to the tank, the fuel lines, the fuel filter and clean fuel through the entire circuit. Driving the children to Killingholme Primary School is one sort of trip. Any distance on the M180, under 10 miles from Habrough, means the engine working hard throughout, and a run to Kingston upon Hull, under 10 miles away, makes a very different task too.
Driven till it protested. Rattling, 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 stops: a lay-by, a side street, the verge on Cravens Lane. Permanent damage is very unusual when a car is pulled over early, and the drain and flush-through that still come first sort it out.
Myths Habrough drivers hear about petrol in a diesel
It will not be fine. The myth: "Fill it the rest of the way with diesel and it will be." Nothing is removed when you top up — the tank simply holds more of the same mixture. The assumption behind that guidance — that diesel fuel systems tolerate petrol by percentage — is wrong.
Myth: "A current diesel can cope with a bit of petrol." If anything, the opposite. At higher pressure, through smaller components: that is how a modern diesel moves its fuel, and so the protection counts for more, not less.
Myth: "If it starts and drives, there's no damage done." This is the one that catches people. A petrol motor fed diesel usually will not run, so the motorist stops and the damage stops with them. Nothing seems to have happened when a diesel fed petrol fires up, ticks over and drives away, as it usually does; meanwhile your pump wears. Being able to run is not proof of being fine.
Not so: a two-stroke additive makes it safe to drive home. It is an old workaround, meant for another fault. It doesn't put back what petrol has thinned, and the petrol is still in that tank after that.
Myth: "Drain that tank yourself and you are sorted." After the motor has run, some of the petrol is no longer inside the tank: it's in the fuel filter and the fuel lines, and it goes straight back through the pump at your next start. Also, a can of petrol drained by the kerbside is genuinely hazardous.
How it happens: petrol in a diesel
It's seldom carelessness, and no one does it on purpose. The petrol nozzle is the narrower of the two and slides into a diesel filler with almost no resistance; a diesel nozzle generally will not go into a petrol vehicle at all. The forecourt makes it simple, and the slip runs one way.
The moment routine stops matching your car is the moment it occurs. Hire cars, courtesy cars, and motors that are new to you. A household with one petrol and one diesel on the driveway. Your ordinary forecourt, its pumps suddenly in a different order. A hurried fill on the way to the nearest station with a train to catch. A new-to-you diesel Skoda Octavia, its first fuelling, and a motorist accustomed to petrol: exactly when it takes place. With rain, a call coming in, or children to deal with, your hand just does what it has always done.
Next time you fill up in Habrough: preventing petrol in a diesel
- Not every forecourt in the UK keeps to green for unleaded and black for diesel, even if most generally do. Read the petrol pump's label; the colour is only a hint.
- Check the filler flap. Many cars state the fuel inside the flap or on the cap. Look at it on the first fill in a motor you do not know.
- Mark the key. In a household with one of each, a coloured fob or a sticker on your diesel's key does more than any amount of meaning to remember.
- "Diesel", aloud, before you pick up the nozzle — each time a new or hired car gets its first tank. It sounds silly. It does the trick.
- Thinking about something else is when this becomes an easy mistake to make, so put your phone away then keep your mind on the petrol pump.
- Up to a point, a misfuel inhibitor helps: some diesels have a filler built to refuse a petrol nozzle, and add-on devices exist for the remainder. Count it as a backstop, then keep checking the petrol pump.
- Spotting it mid-fill? Stop there and then. A thinner mix follows from less petrol in the tank, yet the next stage remains the same: do not crank it.
Habrough: already put petrol in a diesel?
Short and simple, then, is the order of things. Starting it is out, and so is turning on your ignition. If you are still on the forecourt — JET or anywhere else — ask the attendants to help you roll it away from the petrol pump. Then call 0333 366 0103 and tell us what was put in, roughly how much, and whether it's run.
Corrosion and deposits are the problem with AdBlue, whereas petrol means lost lubrication. So if it was AdBlue, say so — and see its own Habrough page.
Why one petrol in a diesel job around Habrough costs more than another
The four situations above are four different jobs, so no single price for this would be fair. Mostly, your cost moves with which one you're in. Where the vehicle is matters too, and whether a van can safely reach it, after the ratio of petrol to what your tank takes.
Before any quote, not after, come three questions: the fuel that was put in, its quantity, and if it's run. That's why. Given the answers, you get a straight figure rather than a range.
About Habrough, briefly
Habrough is a small village in North Lincolnshire, situated near the Humber Estuary and approximately 9.9 miles from Kingston upon Hull. Habrough sits at a low elevation of around 17 metres above sea level, in an area of gently rolling countryside. Habrough has a population of around 591 people, with a predominance of detached housing. Habrough is close to nearby villages such as Brocklesby and Ulceby Skitter.
Habrough and Lincolnshire: where our fuel drain cover reaches
Petrol in diesel call-outs around Habrough — part of the DN postcode area — go to teams that likewise cover the spots about it, Brocklesby, South Killingholme and Ulceby Skitter among them. The vehicle does not need to move to us: our technicians drain at a forecourt, in a supermarket car park, in a lay-by or on your own driveway.
Still at the pump around Habrough?
In that case, you could not be in a better place. Turned off it stays; then phone.