Should You Worry? Petrol in a Diesel Car in Tondu
Less than you likely are, if it hasn't been started. "Have I ruined it?" is the first thing anyone in Tondu asks, and the truthful answer is usually no, because petrol resting in a diesel tank hurts nothing until it's dragged through the fuel system — by ignition priming, by the starter, or by being driven. Leave your engine off and phone Petrol in Diesel — that keeps it like that. Below, this page sets out what petrol actually does inside a diesel, how far it may have gone, and how to stop it happening to you a second time.
Inside your engine: what petrol in a diesel does
Diesel does two jobs on its way through a motor. It burns, and before it combusts it lubricates. The high-pressure pump and the injectors are made to very fine gaps, and your diesel passing through them is what stops those surfaces from wearing against each other.
The second job petrol doesn't do at all, and the first it does poorly. Being less viscous than diesel, petrol strips out the protection a fuel system needs, so a pump running on the blend to wear itself. It is equally made to resist igniting under compression — the reverse of what a diesel needs — which is why you hear the clattering.
The shape of the trouble is plain once you put those together. Contact doesn't do the damage — circulation does. A tank with petrol in it is a fuel issue. The beginning 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 beyond it.
How serious is petrol in a diesel? Four situations we see in Tondu
Fuelled, and not started: no case is better. Just that tank has petrol in it, and so the job is emptying your tank and flushing your system where the car stands. This situation can only truly occur at a forecourt: anywhere else, the car got there by being driven.
A moment's running, or merely the ignition on. The system has been bled, and so petrol has left that tank and got to your filter and the lines. Usually nothing more than clearing, flushing and sorting the fuel filter, and so still straightforward.
A couple of miles driven, and the pump has spent each of them running on weakened fuel. The work is your tank, your lines, your filter and fresh fuel through the whole circuit, and how hard your car was driven matters as much as how far. Driving the kids to the local primary school is one sort of trip. A run as far as Swansea, under 25 miles away, is a very different task. So is any distance on the M4, under a mile from Tondu, where your engine has been running hard the whole time.
Knocking, a lumpy idle, smoke, a throttle gone soft: driven until it complained. The motor is telling you your fuel is no longer acting like diesel. Leave it wherever it stops: a lay-by, a side street, the verge on Iron Way. What goes first is still the drain and flush-through, and that sorts it out, with permanent damage very uncommon if a vehicle is pulled over quickly.
Stories Tondu people hear about petrol in a diesel
"Top it up the rest of the way with diesel and it'll be fine" — a myth. It won't. A bigger tank of the same mixture is all it gives, because topping up removes nothing. Percentage is not how a diesel fuel system tolerates petrol, whatever that guidance presumes.
"Current diesels can handle a little petrol" — a myth, and nearer the reverse. Smaller components and higher pressure are how a current diesel runs its fuel, and that makes the lubrication matter more, not less.
"It starts, it drives, and so there is no harm" — the myth that catches more people than any other. Feed diesel to a petrol engine and it normally won't run, and so the driver stops — and the harm stops with them. Whilst your pump wears, a diesel fed petrol usually starts, ticks over and drives away as if nothing has happened. Running isn't the same as fine.
An outdated workaround for a different issue is behind this one. Myth: "Add some two-stroke oil and drive the car home." It does not put back what petrol has diluted, and that petrol is still inside the tank afterwards.
The next start sends petrol back round your pump out of the fuel lines and the fuel filter, where some of that ends up once your engine has been run. That is why draining the tank yourself doesn't leave you sorted — a myth. It is also truly hazardous to drain petrol into a can by the roadside.
How petrol ends up: petrol in a diesel
It is seldom carelessness, and nobody does it on purpose. One way only, because of the nozzles: the narrower petrol one slides inside a diesel filler with almost no resistance, while the diesel one mostly won't fit a petrol vehicle. That is how the forecourt makes it simple.
Habit and the car getting out of step is how it happens. Courtesy car, hire car, or a motor 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. A rushed fill en route to the nearest station with a train to catch. A new-to-you diesel Volkswagen Passat, its first fuelling, and a motorist used to petrol: exactly when it occurs. With rain, a call coming in, or children to deal with, the hand simply does what it always has.
Tondu drivers: how to avoid petrol in a diesel next time
- The label is what matters, and so read the pump instead of the colour: in the UK unleaded handles are usually green and diesel black, yet not on each forecourt.
- Check your filler flap. Plenty of motors state the fuel inside the flap or on the cap. Look at it on the first fill in a car you do not know.
- A coloured fob or a sticker on the diesel's key does more than any amount of intending to remember, in a household with one of each.
- It sounds silly and it works: on your first fill in a new or hired car, say "diesel" out loud before you lift the nozzle off the pump.
- Put the phone away. This is an easy mistake to make whilst you are thinking about something else.
- A misfuel inhibitor helps, up to a point. Some diesels come with a filler built to block a petrol nozzle, and add-on devices are available for vehicles without one. They are a safety net, not a reason to stop reading the petrol pump.
- Noticing it halfway? Stop at once. A weaker mix follows from less petrol in that tank, but your next stage stays the same: don't start the vehicle.
Petrol already in a diesel around Tondu? Start here
Short and simple, then, is the order of things. Leave it unstarted, with your ignition switched off as well. If you are still at the forecourt — Texaco or anywhere else — ask the staff to help you roll it away from the petrol pump. Ring 0333 366 0103 next, with three facts — the fuel, the rough volume, and whether it's run.
AdBlue, not petrol? Then say so. Corrosion and deposits, not lost protection, make it a separate fault — Tondu has a page just for it.
One petrol in a diesel job in Tondu costs more than another. Why?
Four separate tasks lie behind the four situations above — which is why there's no honest single price. What shifts your cost is mostly which of them you're in. Where your car is matters too, and whether our van can safely get to it, after the share of petrol to what your tank holds.
That is why our technicians ask three queries before costing instead of after: what got in, how much, and whether it's run. Those answers are what change a range into one firm number.
About Tondu
Tondu is a village situated on the riverside in Bridgend, Wales, with a population of around 1892 people. Tondu has a mix of housing types, but detached homes are the most predominant. Tondu is located near several other villages, including Aberkenfig, Sarn, and Fountain, and is approximately 15.6 miles from Swansea. Tondu sits at an elevation of 59 metres above sea level, in a scenic area near the Welsh coast.
Across Bridgend and around Tondu: fuel drain cover
Tondu rests in the CF postcode area, and our teams that answer petrol in diesel jobs there work the spots near it as well — Aberkenfig, Sarn and Fountain among them. No need to bring your vehicle to us. Forecourts, supermarket car parks, lay-bys and your own driveway are all spots we drain.
At the pump around Tondu, still?
No position is better: that is where you are. Keep it off. Ring.