Should You Worry? Petrol in a Diesel Car in Cwmfelinfach
If it has not been started, you can worry far less than you likely are. "Have I wrecked it?" is the first thing everyone around Cwmfelinfach asks, and the honest answer is usually no, because petrol resting in a diesel tank hurts nothing till it is dragged through your fuel system — by ignition priming, by your starter, or by driving. To keep the car that way, phone Petrol in Diesel then leave the motor alone. Below, 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.
Inside the motor: what petrol in a diesel does
Passing through a motor, diesel is doing two things at the same time. It combusts, and before it burns it protects. Very fine gaps are built into your injectors and the high-pressure fuel pump, and only your diesel running through keeps those surfaces from grinding together.
Of those two tasks, petrol handles the first poorly and the second never. The clattering comes from petrol being made not to ignite when compressed, which is precisely the opposite of what a diesel needs. On top of that it is runnier than diesel, it strips away the lubrication the system depends on, and any pump running on that blend is wearing itself.
Together, those make the shape of the problem plain. The damage is done by circulation, not by contact. All a tank with petrol in it amounts to is a fuel issue. Whatever a worn pump sheds travels on, carried by the fuel, into the fuel injectors further along, which is why a pump that has worked on the petrol is where a mechanical issue begins.
Four scenarios our technicians see in Cwmfelinfach: how bad is petrol in a diesel?
The best case there is: filled up, never started. Being at a forecourt is what makes this the case: elsewhere, the vehicle has been driven there to begin with. With that petrol kept inside that tank alone, it's cleared and cleaned on the spot, and nothing more is needed.
Ignition on, or started for a second. The fuel system has been primed, and so petrol has left that tank and reached the fuel filter and the lines. Usually little more than emptying, rinsing and seeing to the filter, so still easy.
Some miles driven, and the pump has spent each of them working on diluted fuel. How hard the vehicle was driven counts as much as how far, and the work covers your tank, your lines, the fuel filter and fresh fuel through the entire circuit. On the school run to the local primary school, the mileage is small. Very different once more: a trip to Newport, under 10 miles away, or some miles on the M4, under 10 miles from Cwmfelinfach, where the engine never stopped labouring hard.
Driven on till it protested — rattling, smoke, a lumpy idle, a soft throttle. That is the engine telling you its fuel no longer is behaving like diesel. Stop on the spot — on the verge on Western Terrace, at the kerb, down a side road — and don't move it. Permanent damage is very rare when a vehicle is pulled over soon, and the fuel drain and flush that still come first sort it out.
Myths Cwmfelinfach people hear about petrol in a diesel
False: topping up to full with diesel makes it fine. It does not. Nothing is removed when you top up — your tank just carries more of the same mixture. Percentage is not how a diesel fuel system copes with petrol, whatever that advice presumes.
Myth: a newer diesel copes with a bit of petrol. If anything, the reverse. At higher pressure, through more precise components: that is how a modern diesel handles its fuel, and so the lubrication matters for more, not less.
This is the one that catches motorists. Myth: "If it starts and drives, there's no damage done." A petrol motor fed diesel normally won't run, and so the driver stops and the harm stops with them. Feed petrol to a diesel and it normally fires up, idles and drives away like nothing happened — all the while its pump is wearing. A running engine doesn't mean fine.
An old workaround for a different problem is behind this one. Myth: "Add some two-stroke oil and drive the car home." It doesn't put back what petrol has thinned, and that petrol is still in that tank later on.
"Drain it yourself and you are sorted" — a myth, because after it has been running some petrol sits in your filter and lines, waiting to go right back through your pump at the next start. It's also really risky to drain petrol into a can at the roadside.
Why petrol in a diesel takes place at all
On purpose? Never. Through carelessness? Seldom, if ever. A diesel nozzle mostly won't 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 error easy, and only in one direction.
It occurs when routine and your car stop matching. A vehicle that is new to you — a hire car, on loan as a courtesy car, or just bought. Two motors on one drive, one petrol, one diesel. A well-known forecourt with the pumps in a different order. A train to catch, and a hurried fill on the way to Crosskeys. The first fill-up in a diesel Volkswagen Golf after years of driving petrol is exactly the moment it happens. Add a back seat full of kids, a phone call or rain, and habit takes over.
Preventing petrol in a diesel next time you fill up around Cwmfelinfach
- Not every forecourt in the UK keeps to green for unleaded and black for diesel, even if most usually do. Read the pump's label; the colour is only a hint.
- Check your filler flap. Many motors state the fuel inside the flap or on the cap. Look at it on the first fill in any motor you don't know.
- Good intentions count for less than a sticker or a fob in a bright colour on the diesel's key when a house has one of each. So label it.
- It sounds silly and it works: on your first fill in a new or hired car, say "diesel" out loud before you take the nozzle off the pump.
- Mistakes like this are straightforward to make whilst your mind is on something else, and so your phone goes away.
- A misfuel inhibitor helps, up to a point. Some diesels come with a filler built to reject a petrol nozzle, and add-on devices are available for motors without one. They are a backstop, not a reason to stop reading the pump.
- Stop the moment you notice. Less petrol inside that tank means a weaker mix. It doesn't change what to do next, which is still not to crank it.
Cwmfelinfach: already put petrol in a diesel?
Then, there is only a short order of things. Never start it, and do not switch your ignition on. If you are still on the forecourt — Esso or anywhere else — ask the attendants to help you push the car clear of the petrol pump. Then ring 0333 366 0103 and tell us what got in, about how much, and if it's run.
Say so if it was AdBlue rather than petrol: it is a separate issue, with its own page for Cwmfelinfach, because AdBlue brings corrosion and deposits instead of lost lubrication.
What makes one Cwmfelinfach petrol in a diesel task cost more than the next
Four separate tasks sit behind the four scenarios above — which is why there's no fair single price. What moves your cost is mostly which of them you are in. Two things follow that: the petrol that got in as a proportion of what your tank takes, then the place the car is in and whether a technician can get to it safely.
Three questions come first, before any quote, instead of after — what went in, how much, has it run — and that is the reason. Given those replies, you get a straight figure instead of a range.
About Cwmfelinfach and its setting
Cwmfelinfach is a village in Caerphilly, situated on the banks of a river at an elevation of 112 metres. Cwmfelinfach lies near the communities of Ynysddu, Brynawel, and Wattsville, and is approximately 8 miles from Newport. Cwmfelinfach has a population of around 1353 people, predominantly living in terraced housing. Cwmfelinfach is located in a region of south Wales, within commuting distance of major cities.
Fuel drain cover across Caerphilly, Cwmfelinfach included
Cwmfelinfach waits in the NP postcode area, and the teams that answer petrol in diesel calls there work the spots near it as well — Ynysddu, Brynawel and Wattsville among them. A forecourt, a supermarket car park, a lay-by or your own driveway are all places our engineers work, and your car does not need to come to us.
In Cwmfelinfach and still at the pump?
The best spot there is, then — that's where you are. Ring, and leave it switched off.