Rotherfield: Petrol in a Diesel Car? How Worried to Be
Probably less than you are now — provided no one has started the vehicle. "Have I wrecked it?" is the first question everyone around Rotherfield asks, and the truthful answer is normally no, because petrol resting in a diesel tank harms nothing till it's dragged through the fuel system — by ignition priming, by your starter, or by being driven. Keep it like that: leave the motor off and call Petrol in Diesel. The rest of this page covers what petrol actually does to a diesel, how to tell how far it has got, and how to make sure it doesn't happen to you again.
The engine and petrol in a diesel: what goes on
Two jobs fall to diesel on its route through a motor. It burns, and before it burns it lubricates. What keeps the surfaces inside the high-pressure pump and the injectors from wearing against each other is the diesel flowing through them — they're built to extremely fine tolerances.
Petrol handles the first task poorly and the second not at all. It is thinner than diesel and removes the protection the fuel system rests on, so a pump running on a petrol mixture 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 knocking comes from.
The shape of the issue is plain once you put those together. Contact does not do the harm — circulation does. Petrol in the tank is a fuel fault. The start of a mechanical one is a pump that has been labouring on that petrol — and whatever a worn pump sheds travels on with your fuel to your injectors beyond it.
How serious is petrol in a diesel? Four situations our technicians see around Rotherfield
The best case there is: filled up, not once started. On a forecourt, and truly only there, the petrol is still confined to the tank — because anywhere else the vehicle was driven to reach it. The task is emptying and flushing on the spot.
Ignition on, or started for a second. Once primed, the system has drawn petrol from the tank up to the filter and the fuel lines. Usually little more than emptying, cleaning and seeing to your filter, so still easy.
Those few miles driven meant your pump working on fuel weakened by petrol the whole way. Tank, lines, filter, then fresh fuel run through the entire system: that is the work, and the way the vehicle was driven matters as much as the miles. A school run to Rotherfield Primary School is one matter. A run as far as Brighton and Hove, under 25 miles away, is a very different job. So is any distance on the M23, under 25 miles from Rotherfield, where your engine has been labouring hard the whole time.
It complained, and only then stopped: smoke, rattling, a throttle gone soft, an idle gone lumpy. The engine is telling you the fuel is no longer acting like diesel. Pull up wherever you are — the verge on High Street, a lay-by, a side street — and leave it where it is. What goes first is still the fuel drain and flush-through, and that deals with it, with long-term damage very unusual if a car is pulled over soon.
Stories Rotherfield drivers hear about petrol in a diesel
Myth: topping up to full with diesel makes it fine. It does not. Topping up takes out nothing; it gives you a fuller tank of the same mixture. The assumption behind the advice — that diesel fuel systems tolerate petrol by percentage — is wrong.
Myth: "A newer diesel can cope with a bit of petrol." If anything, the reverse. A current diesel runs its fuel through finer components at higher pressure, which makes the protection count more, not less.
"It starts, it drives, and so there is no harm" — the myth that trips up most motorists than any other. The motorist of a petrol motor fed diesel normally stops, because it will not run, and the harm stops there. Nothing seems to have happened when a diesel fed petrol fires up, ticks over and drives away, which it usually will; meanwhile the pump wears. Being able to run isn't proof of being fine.
Myth: a two-stroke additive makes it safe to drive home. It was an old fix, meant for another issue. It does not put back what petrol has weakened, and that petrol is still in that tank after that.
Once the motor has been run, part of the petrol sits in your filter and the fuel lines, not the tank — and your next start pulls it straight back through the pump. So the myth "drain that tank yourself and you are sorted" does not hold. It's also really dangerous to drain petrol into a can by the roadside.
Why petrol in a diesel takes place so easily
Nobody does it on purpose, and it's seldom carelessness. One way only, since of the nozzles: the slimmer petrol one slips inside a diesel filler with almost no resistance, while the diesel one generally won't fit a petrol car. That's how the forecourt makes it straightforward.
When routine and the vehicle stop matching, it takes place. Courtesy car, hire car, or a car that is new. One petrol and one diesel on the driveway of the same household. The pumps in a different order on a well-known forecourt. Racing for a train at Crowborough and filling up en route. The first fill-up in a diesel Renault Megane after years of driving petrol is exactly the moment it takes place. Throw in a back seat full of children, a phone call or rain, and habit wins.
How to avoid petrol in a diesel at your next fill-up around Rotherfield
- The label is what counts, and so check the petrol pump instead of the colour: in the UK unleaded handles are normally green and diesel black, but not on each forecourt.
- In a vehicle you do not know, look inside the flap over your filler or at the cap before the first fill: many motors print the fuel type there.
- Good intentions do less than a sticker or a fob in a bright colour on the diesel's key if a household has one of each. So label it.
- "Diesel", aloud, before you lift the nozzle — every time a new or hired car gets its first tank. It sounds daft. It works.
- Mistakes like this are easy to make whilst your mind is on something else, and so the phone goes away.
- A misfuel inhibitor helps, up to a point. Some diesels have a filler built to reject a petrol nozzle, and add-on devices exist for cars without one. They are a safety net, not a reason to stop reading the petrol pump.
- The moment you notice, stop: less petrol inside your tank makes a thinner blend. What to do next does not change, though — still don't start the car.
Put petrol in a diesel around Rotherfield already?
Then the order of things is short. Do not turn the ignition on, and don't start it. If you're still on the forecourt — BP or anywhere else — ask the attendants to help you roll it clear of the petrol pump. Next, 0333 366 0103. We'll ask what went in, roughly how much, and if it's been run.
AdBlue, not petrol? Then say so. Corrosion and deposits, not lost lubrication, make it a different problem — Rotherfield has a page just for it.
One petrol in a diesel task around Rotherfield costs more than another. Why?
The four situations above are four different tasks, so no single quote for this would be fair. Which of them you're in is mostly what moves your cost. Where your car is counts too, and whether a technician can safely reach it, after the proportion of petrol to what that tank takes.
Before any quote, not after, we ask three queries: the fuel that was put in, the amount, and if it has run. That is why. A range becomes a straight figure when those replies are in.
About Rotherfield, for a moment
Rotherfield is a rural village in East Sussex, situated inland at an elevation of around 155 metres. Rotherfield lies approximately 35 miles from London and 22 miles from Brighton and Hove, with nearby places including High Cross, Town Row, and Castle Hill. Rotherfield has a population of around 859 people, predominantly living in detached houses. Rotherfield remains a quiet, residential community with a strong sense of rural character.
Fuel drain cover across East Sussex, Rotherfield included
High Cross, Town Row and Castle Hill are among the spots near Rotherfield that the same teams work, answering petrol in diesel calls across Rotherfield's TN postcode area. A forecourt, a supermarket car park, a lay-by or your own drive are all spots our engineers drain, and the vehicle does not need to come to us.
Rotherfield: still at the petrol pump?
In that case, you couldn't be in a better spot. Switched off it stays; then call.