Petrol in a Diesel Car in Queensferry: How Worried Should You Be?
Provided it has not been started, worry less than you probably are. "Have I ruined it?" is the first thing anyone in Queensferry asks, and the honest answer is normally no, because petrol resting in a diesel tank hurts nothing until it's dragged through the fuel system — by ignition priming, by the starter, or by driving. Petrol in Diesel is who to ring, with your motor kept off, so it remains that way. The remainder of this page covers what petrol really does to a diesel, how to tell how far it has got, and how to make sure it doesn't happen to you again.
What petrol in a diesel does to the motor
Two jobs fall to diesel on its route through a motor. It protects to begin with, and after that does it burn. Built to extremely fine gaps, your injectors and the pump rely on the diesel flowing through them to stop their surfaces wearing against one another.
Badly at the first, not at all at the second: that's petrol. A pump running on a petrol mixture is wearing itself out, since 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 wants from its fuel — and that's where any knocking starts.
The shape of the issue is clear when you put those together. Not contact but circulation is what does the damage. Petrol in a tank is a fuel fault. A pump that has been labouring on that petrol is the start of a mechanical one, and whatever a worn pump sheds moves on with the fuel to your injectors downstream.
Four situations our engineers see around Queensferry: how bad is petrol in a diesel?
Filled up, and not started: nothing beats it. At a forecourt, and really only there, that petrol is still confined to the tank — because everywhere else your car was driven to get to it. The job is draining and rinsing on the spot.
Ignition on, or started for a moment. Petrol has come out of your tank and got to the fuel filter and the lines, since the fuel system has been bled. Drain, flush, deal with your filter: still normally simple.
Some miles driven, and your pump has spent each of them running on thinned fuel. How hard the car was driven counts as much as how far, and this work takes in your tank, your lines, the filter and fresh fuel through the whole circuit. On the school run to Saughall All Saints Church of England Primary School, the miles is short. Getting as far as Chester, under 10 miles away, makes a very different job — as does any mileage on the M56, under 5 miles from Queensferry, with the motor labouring hard the whole time.
Driven until it protested. Rattling, an uneven idle, smoke, a throttle that has gone soft. The fuel isn't acting like diesel any more, and your motor is telling you. Stop wherever you are — the verge on Station Road, a lay-by, a side street — and leave the vehicle there. What comes first is still the drain and flush, and that sorts it out, with permanent damage very rare if a car is stopped early.
Petrol in a diesel stories Queensferry drivers hear
Myth: topping up to full with diesel makes it fine. It does not. A fuller tank of the same mix is all it gives, because topping up removes nothing. That guidance supposes a diesel fuel system handles petrol by percentage. It does not.
Myth: "A current diesel can cope with a bit of petrol." If anything, the opposite. Lubrication matters more on newer diesels, not less, since their fuel runs through smaller parts at higher pressure.
This is the one that fools drivers. Myth: "If it starts and drives, there is no damage done." Diesel in a petrol motor generally means a motor that will not run: the driver stops, and so does the harm. Feed petrol to a diesel and it usually starts, ticks over and drives away like nothing has happened — all while its pump is wearing. Being able to run is not proof of being fine.
Not so: a two-stroke additive makes it safe to drive home. It is an old fix, supposed for another issue. What petrol has diluted stays thinned, and that petrol stays inside that tank anyway.
The next start sends petrol back round your pump from the lines and your filter, where some of it sits once the motor has been run. That is why draining your tank yourself does not sort it — a myth. And, a can of petrol drained at the roadside is genuinely hazardous.
Why petrol in a diesel occurs so easily
Nobody does it on purpose, and it's rarely carelessness. The petrol nozzle is the slimmer of the two and slides into a diesel filler with almost no resistance; a diesel nozzle mostly will not go into a petrol motor at all. The forecourt makes it simple, and the slip runs one way.
When habit and your car stop matching, it takes place. Hire cars, courtesy cars, and motors that are new to you. A household with one petrol and one diesel on the drive. The pumps in a different order on a well-known forecourt. Fuelling up in a hurry on the way to Shotton, with a train to catch. The first fill-up in a diesel Volkswagen Golf after years of driving petrol is exactly the moment it takes place. The hand does what it has always done once you add rain, a phone call or a back seat full of kids.
How to prevent petrol in a diesel at your next fill-up around Queensferry
- The label is what matters, and so check the pump instead of the colour: in the UK unleaded handles are usually green and diesel black, but not on each forecourt.
- The first fill in an unfamiliar vehicle is the time to check your filler flap — on it, or on the cap, plenty of motors state the fuel they take.
- Good intentions count for less than a sticker or a fob in a bright colour on your diesel's key when a house has one of each. So label it.
- It sounds daft and it works: on your first fill in a new or hired car, say "diesel" aloud before you take the nozzle off the petrol pump.
- Mistakes like this are simple to make whilst your mind is on something else, and so the phone goes away.
- Some diesels have a filler built to reject a petrol nozzle, and devices you can add are available for vehicles without one. Such an inhibitor helps up to a point — as a safety net, not a reason to stop checking the petrol pump.
- Less petrol means a weaker mix, so stop the moment you realise — while remembering that your next step is unchanged. It is still not to crank it.
Petrol already in a diesel around Queensferry? Start here
In that case, there is just a short order of things. Don't switch the ignition on, and don't start it. If you're still at the forecourt — Asda or anywhere else — ask the attendants to help you push it clear of the petrol pump. Next, 0333 366 0103. We'll ask what got in, about how much, and if it has been run.
Say so if it was AdBlue rather than petrol: it's a separate problem, with its own page for Queensferry, because AdBlue brings corrosion and deposits rather than lost lubrication.
Why one petrol in a diesel job in Queensferry costs more than another
Four separate jobs lie behind the four situations above — which is why there's no fair single quote. What shifts the cost is mostly which of them you are in. Next it is the share — how much petrol was put in against how much that tank takes — and after that where the vehicle is and whether a technician can reach it safely.
Three queries come first, before quoting, rather than after — what got in, how much, has it run — and this is the reason. A range turns into a straight figure when those replies are in.
About Queensferry and where it is
Queensferry is a small village in Flintshire, Wales, situated on the banks of the River Dee at a low elevation of around 8 metres. Queensferry has a mix of housing types, but terraced houses are predominant, and it is located near other communities such as Pentre and Shotton. Queensferry is close to the English border, with Chester just 5.6 miles away, and it is approximately 169.4 miles from London.
Across Flintshire and in Queensferry: fuel drain cover
Pentre, Shotton and Mancot Royal are among the places around Queensferry that the same vans work, answering petrol in diesel jobs across Queensferry's CH postcode area. The car doesn't need to come to us: our engineers drain at a forecourt, in a supermarket car park, in a lay-by or on your own driveway.
Still at the pump in Queensferry?
Then you're in the best place there is. Keep it off. Phone.