Petrol in a Diesel Car in New Town: How Worried Should You Be?
If it has not been started, you can worry less than you likely are. "Have I wrecked it?" is the first question anyone around New Town asks, and the truthful answer is usually no, since petrol resting in a diesel tank hurts nothing until it's drawn through the system — by ignition priming, by the starter, or by driving. To keep the vehicle like that, ring Petrol in Diesel then leave your engine switched off. The rest of this page sets out what petrol actually does to a diesel, how to judge how far it has got, and how to make sure it does not happen to you again.
What petrol in a diesel does to your engine
Passing through a motor, diesel does two things at the same time. It lubricates to begin with, and after that does it burn. Built to extremely fine tolerances, the injectors and the pump depend on the diesel moving through them to stop their surfaces wearing against one another.
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 mixture to wear itself. It is equally made to resist igniting under compression — the opposite of what a diesel needs — which is where you get the clattering.
Put these together and the shape of the trouble is clear. Not contact but circulation is what does the damage. Any tank with petrol in it is a fuel issue. A pump that has been running on that petrol is the start of a mechanical one, and whatever a worn pump sheds moves on with the fuel to the injectors further on.
Four scenarios we see in New Town: how serious is petrol in a diesel?
The best case there can be: filled up, never started. On a forecourt, and really only there, the petrol is still limited to that tank — because everywhere else the car was driven to reach it. The task is draining and cleaning on the spot.
A moment's running, or merely the ignition on. The fuel system has been bled, so petrol has left the tank and got to the fuel filter and the lines. That is generally still a simple job — a drain, a flush, and your filter seen to.
Driven a few miles. Now your pump has spent these miles labouring on thinned fuel. The work is your tank, your lines, the fuel filter and fresh fuel through the entire system, and how hard your car was driven counts as much as how far. On the school run to Sidmouth Church of England (VA) Primary School, the miles is short. Any distance on the M5, under 15 miles from New Town, means your engine has worked hard throughout, and a run to Exeter, under 15 miles away, is a very different job as well.
It protested, and only then stopped: smoke, clattering, a throttle gone soft, an idle gone ragged. What you are hearing is the motor reporting fuel that no longer acts like diesel. Leave it wherever it has stopped: a lay-by, a side street, the verge on Milford Avenue. Permanent damage is very unusual if a car is pulled over soon, and the drain and flush that still go first deal with it.
Myths New Town drivers hear about petrol in a diesel
Myth: topping up to full with diesel makes it fine. It doesn't. Nothing is removed when you top up — your tank simply holds more of the same blend. Percentage isn't how a diesel fuel system copes with petrol, however much that guidance supposes.
Myth: "A current diesel can cope with a bit of petrol." If anything, the opposite. Protection counts more on modern diesels, not less, because their fuel passes through smaller components at higher pressure.
One myth that catches people out: if it starts and drives, it must be unharmed. Feed diesel to a petrol engine and it generally will not run, so the motorist stops — and the damage stops with them. Whilst the pump grinds, a diesel fed petrol usually starts, idles and drives away as though nothing has happened. Being able to run is not the same as being fine.
"A drop of two-stroke oil and drive it home" — a myth, borrowed from a fix from years ago, for a separate problem. None of what petrol thinned is put back by it — and later, that tank still holds that petrol.
Once your engine has run, part of that petrol sits in your filter and your lines, not your tank — and the next start sends it straight back through your pump. So the myth "drain that tank yourself and you are sorted" doesn't hold. On top of that, petrol emptied into a can by the road is truly hazardous.
How does petrol in a diesel occur?
On purpose? Never. Through carelessness? Rarely, if ever. A diesel nozzle mostly will not fit a petrol motor, yet the smaller petrol nozzle goes into the filler of a diesel almost without resistance — so forecourts make this one mistake simple, and just in that direction.
The moment routine stops matching your car is the moment it occurs. Courtesy car, hire car, or a motor that is new. Households running one of each, petrol and diesel. Your ordinary forecourt, its pumps now in a different order. A hurried fill on the way to Feniton with a train to catch. The first fill-up in a diesel Volkswagen Passat after years of driving petrol is exactly the moment it happens. Your hand repeats what it has always done when you add rain, a phone call or a back seat full of kids.
Next time you fill up in New Town: avoiding petrol in a diesel
- The label is what matters, so check the petrol pump instead of the colour: in the UK unleaded handles are usually green and diesel black, yet not on every forecourt.
- Inspect the filler flap. Many vehicles state the fuel type inside the flap or on the cap. Look at it on your first fill in a car you do not know.
- One of each in the house? Mark the key to your diesel — a bright fob, a sticker — since intending to remember is not enough.
- Say it before you lift it. On the first fill in a new or hired car, say "diesel" aloud before you take the nozzle off the petrol pump. It sounds daft and it works.
- Mistakes like this are simple to make while your mind is on something else, so the phone goes away.
- A misfuel inhibitor helps, up to a point. Some diesels come with a filler designed to block a petrol nozzle, and add-on devices exist for motors without one. They are a backstop, not a reason to stop checking the pump.
- Noticing it halfway? Stop there and then. A weaker mix results from less petrol in the tank, yet your next step remains the same: don't fire it up.
Already put petrol in a diesel in New Town?
Short and simple, then, is the order of things. Leave it unstarted, with your ignition switched off as well. If you are still on the forecourt — the nearest petrol station or anywhere else — ask the attendants to help you roll the car away from the pump. Ring 0333 366 0103 next, with three answers — your fuel, the rough quantity, and whether it's run.
Corrosion and deposits form the issue with AdBlue, whereas petrol brings lost protection. So if it was AdBlue, say so — and see its own New Town page.
New Town petrol in a diesel jobs: why one costs more than another
Four different tasks sit behind the four situations above — which is why there is no honest single quote. The situation itself does most of the work of moving your cost. The ratio counts next, meaning how much of your tank is petrol, followed by the position of the vehicle and whether getting to it is safe for a technician.
That is why our engineers ask three queries before quoting rather than after: what got in, how much, and whether it has run. Their replies are what change a range into one firm number.
About New Town itself
New Town is a suburban area in Devon, situated on the coast at a low elevation of around 9 metres. New Town lies near the city of Exeter, approximately 13 miles to the south, and is close to other nearby places such as Sidmouth. New Town has a population of around 3179 people and is characterised by predominantly terraced housing.
Fuel drain cover around New Town and across Devon
Sidmouth, Eastern Town and Land Part are among the locations near New Town that the same vans work, answering petrol in diesel jobs across New Town's EX postcode area. A forecourt, a supermarket car park, a lay-by or your own driveway are all spots we work, and the car doesn't need to move to us.
New Town: still at the pump?
In that case, you could not be in a better position. Keep it off. Phone.