Petrol in a Diesel Car in Raglan: How Worried Should You Be?
Probably less than you already are — provided nobody has started the car. Petrol resting in a diesel tank does nothing to your engine till something pulls it through the fuel system — the ignition priming your pump, your starter, or the drive on its own. So the honest answer to the first query everyone in Raglan asks, "have I ruined it?", is normally no. Petrol in Diesel is who to phone, with the motor left off, so it remains that way. Below, you will find 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
On its way through a motor, diesel does two tasks. Before it combusts, it protects — then it ignites. Made to very fine tolerances, the injectors and the pump depend on the diesel flowing through them to keep their surfaces from 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 wearing itself. It's also made to resist igniting under compression — the reverse of what a diesel needs — which is where you get the knocking.
Together, those leave the shape of the problem clear. Contact does not do the harm — movement does. All a tank with petrol in it amounts to is a fuel fault. A pump that has been working on that petrol is the start of a mechanical one, and whatever a worn pump sheds travels on with the fuel to the injectors further on.
Petrol in a diesel in Raglan: how bad is it? Four situations
The best case there is: filled up, not once started. On a forecourt, and really only there, the petrol is still limited to that tank — since everywhere else your car was driven to get to it. The job is draining and flushing on the spot.
Ignition on, or started for a moment. Your system has been primed, so petrol has left your tank and got to the fuel filter and your lines. That is generally still an easy job — a drain, a flush, and your filter dealt with.
The pump has worked a couple of miles on diluted fuel — that's what driving it meant. Mileage is only half of that; how hard it was driven matters equally. Either way the work includes the tank, the lines, your filter and clean fuel through the whole system. On the school run to the local primary school, the mileage is short. Getting as far as Newport, under 15 miles away, makes a very different task — as does any distance on the M4, under 15 miles from Raglan, with the engine running hard all the way.
Driven on until it protested — rattling, smoke, a lumpy idle, a dead throttle. That is the engine telling you its fuel has stopped acting like diesel. Leave it wherever it has stopped: a lay-by, a side street, the verge on High Street. Permanent damage is very uncommon when a vehicle is pulled over quickly, and the drain and flush that still come first take care of it.
Stories Raglan motorists hear about petrol in a diesel
It will not be fine. The myth: "Fill it the rest of the way with diesel and it'll be." Nothing is removed by topping up — you're left with a bigger tank, still the same mix. A diesel fuel system does not accept petrol by percentage in the way that guidance supposes.
If anything, the opposite holds. Myth: "A current diesel can cope with a bit of petrol." At higher pressure, through smaller components: that is how a modern diesel moves its fuel, so the lubrication matters for more, not less.
This is the one that catches motorists. Myth: "If it starts and drives, there is no damage done." The driver of a petrol engine fed diesel normally stops, because it will not run, and the harm stops with them. A diesel fed petrol generally starts, idles and drives away as though nothing has happened, while the pump grinds. Being able to run isn't the same as being fine.
Myth: "Add some two-stroke oil and drive it home." It's an old fix for a distinct issue. It does not put back what petrol has weakened, and the petrol is still inside that tank after that.
Once your engine has been run, part of the petrol sits in the filter and the fuel lines, not the tank — and your next start pulls it straight back through your pump. So the myth "drain that tank yourself and you are sorted" doesn't stand up. It is also really hazardous to drain petrol into a can at the roadside.
Petrol in a diesel: how does it happen?
It is seldom carelessness, and no one does it on purpose. The forecourt makes it easy: the petrol nozzle is the slimmer of the two, and it slips into a diesel filler with almost no resistance, whilst a diesel nozzle mostly will not go into a petrol motor at all. So the mistake runs one way.
It occurs when habit and your car stop matching. Hire cars, courtesy cars, and vehicles that are new to you. One petrol and one diesel on the driveway of the same household. The pumps in a different order on a well-known forecourt. Racing for a train outside Abergavenny and filling up en route. The first fill-up in a diesel Volkswagen Golf after years of driving petrol is exactly the moment it happens. The hand does what it has always done once you add rain, a phone call or a back seat full of children.
Next time you fill up around Raglan: preventing petrol in a diesel
- Not every forecourt in the UK follows green for unleaded and black for diesel, even if most generally do. Check the petrol pump's label; the colour is just a clue.
- The first fill in a strange motor is the time to check your filler flap — inside it, or on the cap, many vehicles state which fuel to use.
- Good intentions count for less than a sticker or a fob in a bright colour on the diesel's key when a household has one of each. So mark it.
- "Diesel", out loud, before you lift the nozzle — every time a new or hired car gets its first tank. It sounds daft. It works.
- Put the phone away. This is an easy mistake to make while you're thinking about something else.
- Up to a point, a misfuel inhibitor helps: some diesels come with a filler designed to reject a petrol nozzle, and add-on devices exist for the remainder. Treat it as a backstop, then keep checking the petrol pump.
- Stop the moment you realise. Less petrol in the tank means a thinner mixture. It doesn't change what to do next, which is still not to start it.
Put petrol in a diesel in Raglan already?
The order of things is brief, then. Do not crank it, and don't turn the ignition on. Ask the attendants to help you push it clear of the petrol pump if you are still at the forecourt, whether that is Gulf or anywhere else. Then call 0333 366 0103 and tell us what went in, about how much, and if it has run.
Corrosion and deposits form the problem with AdBlue, where petrol brings lost protection. So if it was AdBlue, say so — and read its own Raglan page.
What makes one Raglan petrol in a diesel job cost more than the next
A fair single price doesn't exist here: four situations, four separate jobs. Which of them you are in is chiefly what moves the cost. The ratio matters next, meaning how much of your tank is petrol, followed by the location of the car and whether getting to it is safe for a technician.
Before any quote, not after, come three queries: your fuel that was put in, its quantity, and whether it's run. That's why. Their replies are what turn a range into one firm number.
About Raglan
Raglan is a village situated on the banks of a river in Monmouthshire, Wales, with an elevation of around 47 metres. Raglan lies approximately 13.7 miles from Newport and 118.3 miles from London, making it a relatively accessible rural community. Raglan has a mix of housing types, but semi-detached homes are particularly prevalent in the area. Raglan is surrounded by smaller settlements, including Cuckoos Row, Wern-y-cwrt, and Twyn-y-Sheriff.
Fuel drain cover across Monmouthshire, Raglan included
Cuckoos Row, Wern-y-cwrt and Twyn-y-Sheriff are among the spots around Raglan that the same teams work, answering petrol in diesel calls across Raglan's NP postcode area. Our technicians drain where the car is — your own drive, a lay-by, a supermarket car park, a forecourt — so it does not have to come to us.
Still at the petrol pump in Raglan?
Then you are in the best spot there can be. Keep it switched off, then ring.