Minera: Petrol in a Diesel Car? How Worried to Be
If it has not been started, you can worry less than you likely are. Everyone in Minera starts with "have I wrecked it?", and the fair answer is generally no: petrol left in the tank of a diesel stays harmless until priming, cranking or driving draws it into your fuel system. To keep the car like that, ring Petrol in Diesel then leave your engine alone. The remainder of this page sets out 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.
What petrol in a diesel does to the engine
On its way through an engine, diesel does two jobs. Before it ignites, it protects — then it ignites. The high-pressure fuel pump and the injectors are made to extremely fine clearances, and your diesel passing through them is what stops those surfaces from wearing against each other.
Of those two jobs, petrol manages the first badly and the second never. A pump working on a petrol blend is wearing itself out, since petrol is thinner than diesel and takes away the lubrication the fuel system depends on. Petrol is also made to resist igniting under compression — the opposite of what a diesel wants from its fuel — and that is where any knocking comes.
Put these together and the shape of the trouble is clear. It is circulation that does the damage, not contact. Petrol in a tank is a fuel issue. A pump that has been working on that petrol is the start of a mechanical one, and whatever a worn pump sheds moves on with your fuel to your injectors further on.
How serious is petrol in a diesel? Four situations our technicians see in Minera
The best case there can be: filled up, never started. Being at a forecourt is what makes this possible: elsewhere, your car has been driven there to begin with. With the petrol held in the tank alone, it's cleared and flushed on the spot, and nothing more is needed.
Your ignition switched on, or a short start. With the fuel system primed, your lines and filter already contain petrol that came from that tank. That's usually still an easy task — a drain, a flush, and the fuel filter dealt with.
Your pump has worked a couple of miles on weakened fuel — that is what driving the vehicle does. Distance is only half of it; how hard it was driven counts equally. Either way the work runs to that tank, the fuel lines, the filter and clean fuel through the whole circuit. Short trips, such as the school run to the local primary school, are one matter. Driving as far as Wrexham, under 5 miles away, makes a very different job — as does any distance on the M56, under 15 miles from Minera, with the engine labouring hard all the way.
Rattling, a ragged idle, smoke, a throttle gone soft: driven until it complained. The fuel isn't acting like diesel any more, and the motor is saying so. Stop on the spot — on the verge on Wern Road, at the kerb, down a side road — and don't move it again. Long-term damage is very rare if a car is pulled over quickly, and the fuel drain and flush-through that still come first deal with it.
What Minera people get told about petrol in a diesel — and the myths in it
Myth: "Fill it the rest of the way with diesel and it'll be fine." It will not. A fuller tank of the same mix is all you get, because topping up takes out nothing. The idea behind the advice — that diesel fuel systems tolerate petrol by percentage — is wrong.
Not so: a modern diesel copes with a bit of petrol. Rather, the opposite. A modern diesel runs its fuel through smaller parts at higher pressure, which makes the lubrication matter more, not less.
Myth: "If it starts and drives, there's no harm done." This is the one that fools motorists. Feed diesel to a petrol engine and it generally won't run, so the motorist stops — and the damage stops with them. Nothing seems to have happened when a diesel fed petrol fires up, ticks over and drives away, which it usually does; meanwhile your pump wears. Running doesn't mean fine.
Myth: "Add some two-stroke oil and drive the car home." It's an old workaround for a distinct issue. It does not put back what petrol has weakened, and the petrol is still inside your tank after that.
Myth: "Drain the tank yourself and you are sorted." After the motor has run, some of the petrol is no longer in your tank: it is in the fuel filter and the fuel lines, and it goes right back through your pump on your next start. Besides, petrol drained into a can by the road is genuinely risky.
How does petrol in a diesel occur?
It is seldom carelessness, and no one does it on purpose. One way only, because of the nozzles: the slimmer petrol one slips inside a diesel filler with almost no resistance, whereas the diesel one generally won't fit a petrol vehicle. That's how the forecourt makes it simple.
When routine and your car stop matching, it happens. Hire cars, courtesy cars, and cars that are new to you. Households running one of each, petrol and diesel. A familiar forecourt with the pumps in a different order. Filling up in a hurry en route to Gwersyllt, with a train to catch. The first fill-up in a diesel Renault Megane after years of driving petrol is exactly the moment it takes place. The hand repeats what it has always done once you add rain, a phone call or a back seat full of children.
How to avoid petrol in a diesel on your next fill-up around Minera
- Check the pump, not the colour. In the UK unleaded handles are normally green and diesel black, yet not on each forecourt. The label is what counts.
- The first fill in a strange car is the time to check your filler flap — inside it, or on the cap, many vehicles state the fuel they take.
- A coloured fob or a sticker on your diesel's key achieves more than any amount of intending to remember, in a home with one of each.
- Say it before you lift it. On your first fill in a new or hired car, say "diesel" out loud before you lift the nozzle off the petrol pump. It seems silly and it works.
- Mistakes like this are straightforward to make while your mind is on something else, and so the phone goes away.
- A misfuel inhibitor helps, up to a point. Some diesels come with a filler designed to reject a petrol nozzle, and add-on devices are available for motors without one. They are a safety net, not a reason to stop reading the pump.
- As soon as you notice, stop: less petrol in that tank means a weaker blend. What to do next doesn't change, though — still do not start it.
Put petrol in a diesel around Minera already?
The order of things is short, then. Don't turn your ignition on, and don't fire it up. If you are still on the forecourt — Asda or anywhere else — ask the staff to help you push it clear of the pump. What went in, roughly how much, and whether it has run: tell us that when you ring 0333 366 0103.
Corrosion and deposits form the issue with AdBlue, where petrol brings lost lubrication. So if it was AdBlue, say so — and see its own Minera page.
What makes one Minera petrol in a diesel job cost more than the next
The four scenarios above are four separate jobs, so no single price for this would be honest. Which of them you're in is mostly what moves the cost. The ratio counts next, meaning how much of that tank is petrol, and then the location of your car and whether reaching it is safe for our van.
Ahead of any quote, not after, we ask three questions: the fuel that got in, its volume, and whether it has run. That is why. A range turns into a straight figure once those answers are in.
About Minera itself
Minera is a small village in Wrexham county, situated on the banks of a river at an elevation of 248 metres. Minera lies close to the city of Wrexham, approximately 4 miles away, and is surrounded by nearby places such as Pentre and Gegin. Minera has a population of around 663 people, predominantly living in detached houses. Minera is located in a rural area, with The Smelt nearby.
Fuel drain cover across Wrexham, Minera included
Pentre, Gegin and The Smelt are among the spots around Minera that the same teams work, answering petrol in diesel jobs across Minera's LL postcode area. The car does not need to come to us: our engineers drain on a forecourt, in a supermarket car park, in a lay-by or on your own driveway.
At the petrol pump in Minera, still?
Then you're in the best position there is. Keep it off. Phone.