Should You Worry? Petrol in a Diesel Car in Penlan
Not started? Then less worried than you probably feel. Until your ignition primes the pump, the starter turns, or the car is driven, petrol in a diesel tank just waits there and does nothing. Which means the truthful reply to that first Penlan query — "have I wrecked it?" — normally no. Keep it that way: leave the engine off then call Petrol in Diesel. The remainder of this page sets out what petrol really does to a diesel, how to judge how far it has got, and how to make sure it doesn't happen to you a second time.
What petrol in a diesel does to the engine
Two jobs fall to diesel on its route round a motor. It ignites, and before it ignites it lubricates. Designed to very fine clearances, your injectors and the pump depend on your diesel moving through them to keep their surfaces from wearing against one another.
Of those two tasks, petrol handles the first badly and the second never. It is thinner than diesel and strips away the protection your fuel system rests on, so a pump running on a petrol blend 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 is where the rattling comes from.
The shape of the issue is clear once you put those together. The damage is done by movement, not by contact. A tank with petrol in it is a fuel problem. A pump that has been running on that petrol is the beginning of a mechanical one, and whatever a worn pump sheds travels on with your fuel to your injectors further on.
Penlan, petrol in a diesel: four situations, from mild to major
Fuelled, and not started: nothing beats it. Being at a forecourt is what makes this possible: elsewhere, your car has been driven there to begin with. With that petrol held in the tank alone, it's emptied and purged right where it stands, and nothing more is needed.
Started for a second, or just the ignition on. The system has been primed, and so petrol has left the tank and got to your filter and the lines. Drain, flush, see to the fuel filter: still usually easy.
Those few miles on the road meant the pump working on fuel thinned by petrol the whole way. Tank, lines, filter, then clean fuel put through the entire system: that's this work, and the way your car was driven counts as much as the mileage. Short trips, like the school run to the local primary school, are one thing. A run as far as St Davids, under 50 miles away, is a very different job. So is any miles on the M4, under 50 miles from Penlan, where your engine has been working hard the whole time.
Driven on till it protested — rattling, smoke, an uneven idle, a dead throttle. The motor is telling you the fuel is no longer acting like diesel. Whether it's the verge on Blaenwern, a lay-by or a side road, stop there then leave it. The drain and flush still come first, and they deal with it: when a vehicle is pulled over quickly, lasting damage is very unusual.
Stories Penlan drivers hear about petrol in a diesel
Myth: "Fill it the rest of the way with diesel and it'll be fine." It will not. A bigger tank of the same mixture is all it gives, because topping up takes out nothing. That guidance assumes a diesel fuel system handles petrol by percentage. It does not.
Myth: a newer diesel copes with a bit of petrol. Rather, the reverse. At higher pressure, through finer components: that's how a current diesel handles its fuel, so the lubrication matters for more, not less.
This is the one that catches motorists. Myth: "If it starts and drives, there's no harm done." Any petrol engine fed diesel usually will not run, and so the driver stops and the damage stops with them. A diesel fed petrol usually starts, ticks over and drives away as if nothing has happened, whilst your pump wears. A running engine does not mean fine.
Myth: "Add some two-stroke oil and drive it home." It's an outdated workaround for a separate problem. None of what petrol weakened gets put back by it — and later, the tank still holds that petrol.
"Drain it yourself and you are sorted" — a myth, since after it has been running some petrol lies in the fuel filter and lines, ready to go straight back through your pump on your next start. On top of that, petrol drained into a can by the road is truly risky.
How does petrol in a diesel occur?
Carelessness is seldom the cause, and no one means to do it. One way only, because of the nozzles: the smaller petrol one slips inside a diesel filler with almost no resistance, whereas the diesel one mostly won't fit a petrol vehicle. That's how the forecourt makes it easy.
It takes place when habit and the car stop matching. Hire cars, courtesy cars, and vehicles that are new to you. Two vehicles on one driveway, one petrol, one diesel. The pumps in a different order on a well-known forecourt. A rushed fill on the way to the nearest station with a train to catch. Precisely the moment it happens: after years of driving petrol, a driver fills a diesel Renault Clio for the first time. Add rain, a phone call or a back seat full of kids, and the hand repeats what it has always done.
Penlan people: how to avoid petrol in a diesel next time
- Check the petrol pump, not the colour. In the UK unleaded handles are normally green and diesel black, but not on each forecourt. The label is what matters.
- Check your filler flap. Many vehicles state the fuel inside the flap or on the cap. Look at it on the first fill in any vehicle you do not know.
- One of each in the household? Label the key to your diesel — a bright fob, a sticker — since meaning to remember isn't enough.
- Say it before you lift it. On the first fill in a new or hired car, say "diesel" aloud before you lift the nozzle off the pump. It sounds silly and it does the trick.
- Mistakes like this are straightforward to make while your mind is on something else, so the phone goes away.
- Up to a point, a misfuel inhibitor helps: some diesels come with a filler built to block a petrol nozzle, and add-on devices are available for the remainder. Count it as a safety net, and keep checking the pump.
- Stop the moment you realise. Less petrol inside the tank makes a weaker mixture. It does not change what to do next, which is still not to fire it up.
Already put petrol in a diesel in Penlan?
Then the order of things is brief. Starting it is out, and so is turning on the ignition. Ask the attendants to help you roll it clear of the pump if you are still on the forecourt, whether that's Texaco or somewhere else. Then call 0333 366 0103 and tell us what was put in, about how much, and whether it has run.
Corrosion and deposits form the problem with AdBlue, where petrol brings lost lubrication. So if it was AdBlue, say so — and read its own Penlan page.
Penlan petrol in a diesel jobs: why one costs more than another
There's no honest single quote for this, because the four scenarios above are four different tasks. What shifts your cost is mostly which of them you're in. The share matters next, meaning how much of your tank is petrol, followed by the location of the vehicle and whether getting to it is safe for a technician.
That is why our technicians ask three queries before pricing instead of after: what was put in, how much, and if it has run. Given those replies, there is a straight figure instead of a range.
About Penlan and where it is
Penlan is a suburban area situated on the riverside in Carmarthenshire, with a relatively low elevation of 55 metres. Penlan lies near several small towns, including Newcastle Emlyn and Adpar, and is approximately 35 miles from St Davids. Penlan has a population of around 846 people, predominantly living in semi-detached housing. Penlan is also located near Aber-Arad, and is about 189 miles west of London.
Penlan and Carmarthenshire: where our fuel drain cover reaches
Newcastle Emlyn, Adpar and Aber-Arad are among the places near Penlan that the same vans work, answering petrol in diesel calls across Penlan's SA postcode area. No need to bring your vehicle to us. Forecourts, supermarket car parks, lay-bys and your own drive are all spots where we work.
In Penlan and still at the petrol pump?
In that case, you could not be in a better spot. Leave the car switched off, then ring.