Should You Worry? Petrol in a Diesel Car in The Down
Not started? Then less worried than you likely feel. Petrol resting in a diesel tank does nothing to the engine until something pulls it through the system — your ignition priming the pump, the starter, or the drive itself. So the truthful answer to the first query anyone around The Down asks, "have I wrecked it?", is usually no. Keep it like that: leave your engine off and call Petrol in Diesel. What petrol actually does to a diesel, how to judge how far it's travelled, and how to stop it from happening again: that's the rest of this page.
Petrol in a diesel: what does it do to your engine?
Two tasks fall to diesel on its route round a motor. It lubricates first, and only then does it burn. Built to very fine gaps, the fuel injectors and your pump rely on your diesel moving through them to keep their surfaces from wearing against one another.
Badly at the first, not at all at the second: that's petrol. The knocking comes from petrol being designed 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 hinges on, and any pump working on such a blend is wearing itself.
The shape of the trouble is plain when you put those together. It is circulation that causes the harm, not contact. Petrol in the tank is a fuel fault. The start of a mechanical one is a pump that has been running on that petrol — and whatever a worn pump sheds moves on with the fuel to your injectors downstream.
The Down, petrol in a diesel: four cases, from mild to major
The best case there can be: filled up, not once started. At a forecourt, and really only there, the petrol is still confined to your tank — since anywhere else the vehicle was driven to reach it. The job is emptying and rinsing on the spot.
Ignition on, or started for a moment. Petrol has come out of that tank and got to the fuel filter and your lines, because the system has been primed. Usually nothing more than draining, flushing and seeing to the filter, so still straightforward.
Some miles driven, and your pump has spent every one of them working on thinned fuel. Tank, lines, filter, then fresh fuel put through the whole circuit: that's the work, and the way the car was driven counts as much as the mileage. On the school run to Castlefields Primary School, the miles is short. Any distance on the M54, under 15 miles from The Down, means the motor working hard throughout, and a run to Wolverhampton, under 25 miles away, makes a very different task as well.
Driven on till it protested — clattering, smoke, a ragged idle, a soft throttle. That's your motor telling you its fuel no longer is behaving like diesel. Pull up on the spot — on the verge on B4364, at the kerb, down a side road — and don't move it again. A vehicle pulled over soon very rarely has long-term damage, because the drain and the flush, which still go first, deal with it.
Petrol in a diesel myths The Down motorists hear
Myth: topping up to full with diesel makes it fine. It doesn't. A bigger tank of the same mixture is all it gives, since topping up removes nothing. Percentage is not how a diesel fuel system copes with petrol, however much that advice presumes.
"Current diesels can handle a little petrol" — a myth, and nearer the opposite. Protection matters more on newer diesels, not less, since their fuel runs through finer components at higher pressure.
This is the one that fools drivers. Myth: "If it starts and drives, there's no harm done." A petrol engine fed diesel usually won't run, so the motorist stops and the harm stops with them. While the pump wears, a diesel fed petrol normally starts, idles and drives away as though nothing has happened. Running doesn't mean fine.
Not so: a two-stroke additive makes it safe to drive home. It is an old fix, meant for another fault. None of what petrol thinned is put back by it — and afterwards, that tank still holds that petrol.
The next start sends petrol back round the pump from the fuel lines and your filter, where some of that sits after the motor has been run. That's why a DIY tank drain does not sort it — a myth. Besides, petrol cleared into a can by the road is genuinely dangerous.
How does petrol in a diesel occur?
A careless moment is rarely the cause, and nobody means to do it. A diesel nozzle generally will not fit a petrol vehicle, but the slimmer petrol nozzle goes into the filler of a diesel nearly without resistance — so forecourts make this one mistake straightforward, and only in one direction.
Habit and the vehicle falling out of step is when it occurs. Courtesy car, hire car, or a car that is new. Two motors on one driveway, one petrol, one diesel. A forecourt you know, only with its pumps laid out differently. A rushed fill on the way to Shifnal with a train to catch. Exactly the moment it takes place: after years of driving petrol, a driver fills a diesel Volkswagen Tiguan for the first time. Your hand repeats what it has always done when you add rain, a phone call or a back seat full of kids.
The Down drivers: how to avoid petrol in a diesel next time
- Not every forecourt in the UK keeps to green for unleaded and black for diesel, though most generally do. Read the petrol pump's label; the colour is just a clue.
- Inspect the filler flap. Plenty of vehicles state the fuel type inside the flap or on the cap. Look at it on the first fill in a car you do not know.
- Good intentions do less than a sticker or a fob in a bright colour on your diesel's key when a house has one of each. So mark it.
- "Diesel", out loud, before you pick up the nozzle — each time a new or hired car gets its first tank. It sounds silly. It does the trick.
- Tuck the phone away. This is an easy mistake to make while you're thinking about something else.
- A misfuel inhibitor helps, up to a point. Some diesels have a filler built to refuse a petrol nozzle, and add-on devices are available for vehicles without one. They are a safety net, not a reason to stop checking the petrol pump.
- Less petrol means a thinner mix, and so stop the moment you notice — while remembering that your next step is unchanged. It's still not to start the vehicle.
Already put petrol in a diesel in The Down?
Short and simple, then, is the order of things. Do not turn the ignition on, and do not fire it up. Still on the forecourt, at Esso or anywhere else? Ask the staff to help you roll the vehicle away from the petrol pump. Next, 0333 366 0103. We will ask what was put in, roughly how much, and if it's been run.
Corrosion and deposits are the trouble with AdBlue, where petrol means lost lubrication. So if it was AdBlue, say so — and read its own The Down page.
One petrol in a diesel task in The Down costs more than another. Why?
Four separate tasks lie behind the four scenarios above — which is why there is no honest single price. What shifts the cost is mostly which of them you are in. The proportion matters next, meaning how much of the tank is petrol, and then the location of your car and whether getting to it is safe for a van.
What got in, how much, and if it has run — three queries our engineers ask before pricing, not after, for precisely that reason. The replies turn a range into a straight figure.
About The Down and where it is
The Down is a locality in Shropshire, situated on the riverside at an elevation of 137 metres, with detached housing being the predominant type of accommodation. The Down lies approximately 15 miles from Wolverhampton and 121 miles from London, making it a relatively rural area within the West Midlands region. The Down is surrounded by other small places, including Defford, Eudon Burnell, and Eudon George, and has a population of around 579 residents. The Down benefits from its scenic riverside setting, which adds to its appeal as a residential area.
Fuel drain cover across Shropshire, The Down included
Defford, Eudon Burnell and Eudon George are among the places near The Down that the same vans work, answering petrol in diesel call-outs across The Down's WV postcode area. We drain where your vehicle is — your own drive, a lay-by, a supermarket car park, a forecourt — so it does not have to come to us.
At the pump around The Down, right now?
The best place there is, then — that's where you are. Keep it off. Call.