New England: Petrol in a Diesel Car? How Worried to Be
Likely less than you are now — provided nobody has started the vehicle. Petrol resting in a diesel tank does nothing to the motor till something draws it through the fuel system — the ignition priming the pump, your starter, or driving on its own. So the fair answer to the first question everyone in New England asks, "have I ruined it?", is usually no. Petrol in Diesel is who to call, with your engine left off, and so it remains that way. Further down, you will find what petrol actually does inside a diesel, how far it might have got, and how to stop it happening to you a second time.
Petrol in a diesel: what does it do to the motor?
Passing through a motor, diesel is doing two jobs at the same time. It burns, and before it burns it lubricates. The high-pressure pump and the fuel injectors are designed to extremely fine gaps, and the diesel passing through them is what stops those surfaces from grinding against each other.
Of these two tasks, petrol handles the first poorly and the second not at all. A pump working on a petrol mixture is wearing itself out, since petrol is thinner than diesel and takes away the lubrication the fuel system relies on. Petrol is also designed to resist igniting under compression — the opposite of what a diesel needs from its fuel — and that is where the clattering comes.
Combined, those leave the shape of the trouble plain. Contact does not do the damage — movement does. Petrol in the tank is a fuel problem. After the pump has been labouring on that petrol, a mechanical issue has started: whatever is shed by a pump that's wearing travels downstream to your injectors with the fuel.
Four scenarios we see in New England: how bad is petrol in a diesel?
The best case there is: filled up, never started. Being on a forecourt is what makes this the case: elsewhere, the car has been driven there to begin with. With the petrol kept inside the tank alone, it is emptied and cleaned right where it stands, and nothing more is needed.
Ignition on, or started for a second. Once primed, your system has drawn petrol out of the tank up to your filter and the lines. Drain, flush, deal with your filter: still normally easy.
Those few miles on the road meant the pump running on fuel thinned by petrol the whole way. How hard the vehicle was driven counts as much as how far, and the work covers the tank, your lines, your filter and clean fuel through the entire circuit. Driving the kids to The Redstart Primary School is one sort of trip. Very different again: a trip to Wells, under 50 miles away, or any mileage on the M5, under 10 miles from New England, where the motor kept working hard.
Driven on till it protested — knocking, smoke, a lumpy idle, a dead throttle. That's your motor telling you its fuel no longer is behaving like diesel. Pull up wherever you are — the verge on New England, a lay-by, a side street — then leave it where it is. The drain and flush-through still come first, and they take care of it: if a car is pulled over quickly, permanent damage is very unusual.
What New England motorists get told about petrol in a diesel — and the stories in it
It will not be fine. The myth: "Fill it the rest of the way with diesel and it'll be." Topping up takes out nothing; it gives you a fuller tank of the same mix. That guidance presumes a diesel fuel system tolerates petrol by percentage. It does not.
Myth: "A current diesel can cope with a bit of petrol." If anything, the opposite. A modern diesel runs its fuel through smaller components at higher pressure, which makes the lubrication matter more, not less.
Myth: "If it starts and drives, there's no damage done." This is the one that fools drivers. Feed diesel to a petrol motor and it normally will not run, so the driver stops — and the harm stops with them. Feed petrol to a diesel and it generally fires up, ticks over and pulls away as if nothing has happened — all while its pump wears. Fine and running are not the same at all.
Myth: "Add some two-stroke oil and drive the vehicle home." It is an outdated fix for a separate fault. That petrol is still in your tank afterwards, and whatever it has diluted is not put back.
Myth: "Drain your tank yourself and you are sorted." After the engine has run, some of that petrol is no longer in the tank: it's in the filter and your lines, and it goes right back through the pump at your next start. On top of that, petrol emptied into a can by the road is genuinely hazardous.
Petrol in a diesel: how does it occur?
Carelessness is rarely the cause, and nobody means to do it. A diesel nozzle mostly will not go into a petrol motor, but the slimmer petrol nozzle goes into the filler of a diesel almost without resistance — so forecourts make this one mistake straightforward, and only in one direction.
The moment habit stops matching the car is the moment it takes place. A new car, a hire car or a courtesy car. Households running one of each, petrol and diesel. A familiar forecourt with the pumps in a different order. A train to catch, and a rushed fill on the way to Crewkerne. The first fill-up in a diesel Volkswagen Golf after years of driving petrol is precisely the moment it happens. The hand repeats what it has always done once you add rain, a phone call or a back seat full of children.
Next time you fill up in New England: avoiding petrol in a diesel
- The label is what counts, and so read the pump instead of the colour: in the UK unleaded handles are normally green and diesel black, but not on each forecourt.
- Inspect the filler flap. Many cars state the fuel inside the flap or on the cap. Look at it on the first fill in a vehicle you don't know.
- One of each in the home? Mark your key to your diesel — a coloured fob, a sticker — because intending to remember isn't enough.
- Before the nozzle leaves the pump the first time you fuel a hired or new vehicle, say "diesel" aloud. Silly, yes, yet it works.
- Mistakes like this are straightforward to make while your mind is on something else, so your phone goes away.
- Some diesels have a filler designed to reject a petrol nozzle, and devices you can add exist for vehicles without one. Such an inhibitor helps up to a point — as a safety net, not a reason to stop reading the petrol pump.
- Noticing it mid-fill? Stop at once. A thinner blend results from less petrol inside that tank, yet the next step stays the same: do not crank it.
Already put petrol in a diesel in New England?
The order of things is brief, then. Leave it unstarted, with your ignition switched off as well. The attendants at the forecourt — whether at Tesco itself or wherever you filled up — will normally help push it away from the petrol pump if you ask. Next, 0333 366 0103. We will ask what went in, roughly how much, and if it has been run.
Corrosion and deposits are the issue with AdBlue, whereas petrol means lost protection. So if it was AdBlue, say so — and see its own New England page.
What makes one New England petrol in a diesel job cost more than the next
Four separate tasks lie behind the four scenarios above — which is why there is no honest single price. What shifts your cost is mostly which of them you're in. The ratio counts next, meaning how much of the tank is petrol, and then the location of the car and whether getting to it is safe for a van.
Before any quote, not after, come three queries: the fuel that got in, the quantity, and if it has run. That's why. A range turns into a straight figure when the replies are in.
About New England
New England is a small hamlet in inland Somerset, situated at an elevation of 86 metres, and is located near the villages of Hornsbury and Cuttifords Door. New England lies approximately 25 miles from the city of Wells and is characterized by its semi-detached housing. New England is a rural community, set in the South West region of England, and is about 130 miles west of London. New England is also close to the hamlet of Nimmer.
New England and Somerset: where our fuel drain cover runs
Hornsbury, Cuttifords Door and Nimmer are among the spots near New England that the same teams work, answering petrol in diesel call-outs across New England's TA postcode area. A forecourt, a supermarket car park, a lay-by or your own drive are all places we work, and your vehicle does not need to move to us.
Still at the pump around New England?
In that case, you couldn't be in a better spot. Turned off it stays; then call.