Petrol in a Diesel Car in Tal-y-bont: How Worried Should You Be?
If it has not been started, you can worry far less than you probably are. Till your ignition primes your pump, the starter turns, or the car is driven, petrol in a diesel tank simply waits there and does nothing. Which makes the truthful reply to the first Tal-y-bont query — "have I wrecked it?" — usually no. Petrol in Diesel is who to ring, with your motor left off, and so it remains that way. The remainder of this page explains 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.
Inside your engine: what petrol in a diesel does
Two jobs fall to diesel on its route through a motor. Before it burns, it protects — and then it burns. The high-pressure fuel pump and the fuel injectors are built to very fine tolerances, and the diesel passing through them is what keeps those surfaces from wearing against one another.
Poorly at the first, not at all at the second: that's petrol. A pump working on a petrol mixture is wearing itself out, because petrol is runnier than diesel and takes away the protection your fuel system depends on. Petrol is also made to resist igniting under compression — the reverse of what a diesel needs from its fuel — and that is where any knocking starts.
Combined, those make the shape of the problem clear. Not contact but movement is what does the damage. All a tank with petrol in it amounts to is a fuel problem. A pump that has been labouring on that petrol is the beginning of a mechanical one, and whatever a worn pump sheds moves on with the fuel to the injectors further on.
Petrol in a diesel around Tal-y-bont: how serious is it? Four situations
The best case there is: filled up, never started. On a forecourt, and truly only there, that petrol is still limited to the tank — because everywhere else your car was driven to get to it. The task is draining and rinsing on the spot.
A brief spell of running, or merely the ignition on. Petrol has left that tank and got to the filter and the lines, since your system has been bled. Usually little more than draining, flushing and sorting the fuel filter, and so still easy.
Some miles driven, and your pump has spent each of them running on diluted fuel. Mileage is only half of that; how hard it was driven matters equally. Either way this work includes your tank, the fuel lines, your filter and clean fuel through the whole system. On the school run to the local primary school, the mileage is small. Driving as far as Bangor, over 50 miles away, makes a very different task — as does any mileage on the M4, over 50 miles from Tal-y-bont, with the motor working hard all the way.
Driven until it protested. Clattering, an uneven idle, smoke, a throttle that has gone soft. The engine is telling you the fuel is no longer behaving like diesel. Pull up wherever you are — the verge on Chapel Street, a lay-by, a side street — then leave the vehicle there. Lasting damage is very rare if a vehicle is pulled over early, and the drain and flush-through that still go first deal with it.
Petrol in a diesel myths Tal-y-bont people hear
Myth: topping up to full with diesel makes it fine. It doesn't. Topping up takes out nothing; it gives you a bigger tank of the same mix. A diesel fuel system does not tolerate petrol by percentage in the way that guidance presumes.
Myth: "A current diesel can cope with a bit of petrol." If anything, the reverse. Protection matters more on newer diesels, not less, because their fuel passes through smaller components at higher pressure.
Myth: "If it starts and drives, there is no damage done." This is the one that catches drivers. Feed diesel to a petrol engine and it generally will not run, and so the driver stops — and the harm stops with them. Feed petrol to a diesel and it generally starts, ticks over and drives away like nothing happened — all while its pump is wearing. Running does not mean fine.
Myth: "Add some two-stroke oil and drive it home." It's an old fix for a distinct fault. None of what petrol thinned is put back by it — and afterwards, that tank still contains that petrol.
The next start sends petrol back round the pump out of the fuel lines and the fuel filter, where some of that ends up after the motor has run. That is why draining your tank yourself does not leave you sorted — a myth. Emptying petrol into a can at the roadside is also truly dangerous.
How petrol ends up: petrol in a diesel
On purpose? Never. Through carelessness? Rarely, if ever. The petrol nozzle is the narrower of the two and slides into a diesel filler with almost no resistance; a diesel nozzle mostly will not go into a petrol car at all. The forecourt makes it simple, and the mistake runs one way.
When routine and your car stop matching, it takes place. Hire cars, courtesy cars, and vehicles that are new to you. One petrol and one diesel on the driveway of the same household. Your ordinary forecourt, its pumps suddenly in a different order. A hurried fill on the way to Borth with a train to catch. The first fill-up in a diesel Volkswagen Golf after years of driving petrol is precisely the moment it takes place. Throw in a back seat full of kids, a phone call or rain, and the hand takes over.
Tal-y-bont people: how to prevent petrol in a diesel next time
- The label is what matters, and so check the pump rather than the colour: in the UK unleaded handles are usually green and diesel black, but not on every forecourt.
- Many cars state the fuel inside your filler flap or on the cap, so check there on the first fill in a vehicle you don't know.
- Good intentions do less than a sticker or a fob in a bright colour on the diesel's key if a household has one of each. So mark it.
- "Diesel", out loud, before you lift the nozzle — each time a new or hired car gets its first tank. It seems silly. It does the trick.
- Mistakes like this are easy to make while your mind is on something else, so the phone goes away.
- A misfuel inhibitor helps, up to a point. Some diesels have a filler designed to refuse a petrol nozzle, and add-on devices are available for vehicles without one. They are a safety net, not a reason to stop checking the petrol pump.
- The moment you notice, stop: less petrol in that tank means a thinner blend. What to do next doesn't change, though — still do not fire it up.
Tal-y-bont: already put petrol in a diesel?
Then, there's just a short order of things. Starting it is out, and so is turning on the ignition. The staff on the forecourt — whether at murco itself or wherever you filled up — will usually help push it clear of the petrol pump if you ask. Then phone 0333 366 0103 and tell us what was put in, about how much, and whether it's run.
Corrosion and deposits are the problem with AdBlue, where petrol brings lost lubrication. So if it was AdBlue, say so — and see its own Tal-y-bont page.
One petrol in a diesel job around Tal-y-bont costs more than another. Why?
Four separate jobs lie behind the four situations above — which is why there's no fair single quote. The scenario itself does most of the work of moving the cost. Where your car is matters too, and whether our van can safely reach it, after the ratio of petrol to what that tank holds.
What was put in, how much, and whether it has run — three questions our technicians ask before pricing, not after, for precisely that reason. The replies turn a range into a straight figure.
About Tal-y-bont
Tal-y-bont is a small coastal village in Ceredigion, situated at an elevation of around 60 metres and located approximately 177 miles west of London. Tal-y-bont has a mix of housing types, but semi-detached homes are particularly prevalent in the area. Tal-y-bont sits near the coast, close to other small communities like Staylittle, and is within driving distance of larger cities such as Bangor. Tal-y-bont remains a quiet residential community with a population of around 641 people.
Tal-y-bont and Ceredigion: where our fuel drain cover runs
Petrol in diesel call-outs around Tal-y-bont — part of the SY postcode area — go to teams that also cover the spots around it, Adams Street, Birkenhead Street and Staylittle among them. The vehicle does not need to move to us: our technicians drain at a forecourt, in a supermarket car park, in a lay-by or on your own driveway.
In Tal-y-bont and still at the pump?
Nothing beats it: that's where you are. Turned off it stays; then ring.