Drakewalls: Petrol in a Diesel Car? How Worried to Be
Probably less than you already are — provided nobody has started the vehicle. "Have I ruined it?" is the first thing anyone in Drakewalls asks, and the truthful answer is usually no, since petrol left in a diesel tank harms nothing till it is drawn through your fuel system — by ignition priming, by your starter, or by driving. Leave the motor off then call Petrol in Diesel — that keeps it that way. Further down, you will find what petrol really does inside a diesel, how far it may have got, and how to stop it happening to you a second time.
The engine and petrol in a diesel: what happens
Passing through an engine, diesel is doing two jobs at the same time. Lubricating comes before burning; it does both. Made to extremely fine gaps, the injectors and the pump rely on the diesel flowing through them to keep their surfaces from wearing against one another.
Petrol does the first job poorly and the second not at all. The knocking 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 thinner than diesel, it strips out the protection your system hinges on, and any pump working on that mixture is wearing itself.
Taken together, they make clear what shape the problem takes. Not contact but movement is what causes the harm. All a tank with petrol in it amounts to is a fuel fault. The start of a mechanical one is a pump that has been working on that petrol — and whatever a worn pump sheds moves on with the fuel to the injectors downstream.
Four situations our technicians see in Drakewalls: how bad is petrol in a diesel?
Fuelled but not once started — the best it gets. That petrol is in your tank and just your tank, and the job is a drain and a flush where the car stands. This is the one situation that can only really take place at a forecourt, because anywhere else the vehicle has been driven to get there.
Ignition on, or started for a moment. The system has been bled, so petrol has left your tank and reached the filter and your lines. That is usually still a straightforward task — a drain, a flush, and the fuel filter dealt with.
Driven a few miles. Now the pump has spent these miles working on diluted fuel. How hard the vehicle was driven matters as much as how far, and the work takes in the tank, your lines, the filter and clean fuel through the entire system. Short trips, such as the school run to Copper Valley Infant and Nursery Academy, are one thing. A run as far as Plymouth, under 15 miles away, is a very different job. So is any mileage on the M5, under 50 miles from Drakewalls, where your engine has been running hard the whole time.
Clattering, a lumpy idle, smoke, a throttle gone soft: driven until it complained. The fuel isn't acting like diesel any more, and your engine is telling you. Leave it wherever it stops: a lay-by, a side street, the verge on Delaware Road. Long-term damage is very rare if a vehicle is pulled over early, and the drain and flush that still come first take care of it.
Drakewalls motorists and that petrol in a diesel stories they hear
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 are left with a fuller tank, still the same mix. Percentage isn't how a diesel fuel system tolerates petrol, whatever that guidance supposes.
Not so: a modern diesel copes with a bit of petrol. Rather, the reverse. At higher pressure, through more precise parts: that is how a modern diesel handles its fuel, and so the lubrication matters for more, not less.
"It starts, it drives, and so no harm done" — the myth that catches more people than any other. Feed diesel to a petrol motor and it generally won't run, and so the driver stops — and the damage stops with them. Feed petrol to a diesel and it usually starts, idles and drives away as if nothing has happened — all while its pump wears. Running isn't the same as fine.
Not so: a two-stroke additive makes it safe to drive home. It is an old fix, meant for another problem. It does not put back what petrol has diluted, and the petrol is still in that tank afterwards.
"Drain it yourself and you're sorted" — a myth, because after it's been running some petrol lies in the filter and lines, waiting to go straight back through your pump at your next start. Also, a can of petrol filled by the kerbside is genuinely risky.
Why petrol in a diesel takes place so easily
On purpose? Never. Through carelessness? Rarely, if ever. The petrol nozzle is the slimmer of the two and slides into a diesel filler with almost no resistance; a diesel nozzle generally won't go into a petrol car at all. The forecourt makes it simple, and the slip runs one way.
The moment routine stops matching your car is the moment it takes place. Hire cars, courtesy cars, and cars that are new to you. A household with one petrol and one diesel on the driveway. A well-known forecourt with the pumps in a different order. Filling up in a hurry on the way to Gunnislake, with a train to catch. Years of petrol vehicles behind you, a diesel Volkswagen Golf in front of you at the forecourt for its first tank — that is when. With rain, a call arriving, or children to deal with, the hand just does what it always has.
How to prevent petrol in a diesel on your next fill-up around Drakewalls
- Not every forecourt in the UK follows green for unleaded and black for diesel, even if most usually do. Check the pump's label; the colour is just a clue.
- Inspect the filler flap. Plenty of vehicles state the fuel inside the flap or on the cap. Look at it on the first fill in any motor you do not know.
- One of each in the household? Mark your key to your diesel — a coloured fob, a sticker — because meaning to remember isn't enough.
- It sounds silly and it does the trick: on the first fill in a new or hired car, say "diesel" out loud before you take the nozzle off the petrol pump.
- While you are thinking about something else, this is an easy mistake to make — so put the phone away.
- Add-on devices exist for vehicles without one, and some diesels are built with a filler that will not take a petrol nozzle. Helpful — but a safety net at best, never a reason to stop checking the label.
- Less petrol makes a weaker mix, and so stop the moment you notice — though remembering that the next stage is unchanged. It's still not to crank it.
Drakewalls: already put petrol in a diesel?
Then the order of things is brief. Leave it unstarted, with the ignition switched off as well. Ask the staff to help you roll it away from the pump if you're still on the forecourt, whether that is Asda or somewhere else. Next, 0333 366 0103. We'll ask what got in, roughly how much, and if it's been run.
Corrosion and deposits form the trouble with AdBlue, where petrol means lost lubrication. So if it was AdBlue, say so — and see its own Drakewalls page.
Drakewalls petrol in a diesel tasks: why one costs more than another
The four situations above are four separate tasks, so no single price for this would be fair. Which of them you're in is chiefly what moves the cost. After that it's the share — how much petrol went in against how much the tank takes — and after that where the car is and whether our van can reach it safely.
Three queries come first, before any quote, rather than after — what went in, how much, has it run — and that is the reason. Their replies are what turn a range into one firm number.
About Drakewalls itself
Drakewalls is a suburban area in Cornwall, situated inland at an elevation of 184 metres, and is located near the villages of Higher Dimson and Dimson. Drakewalls is characterized by its predominantly detached housing stock and is home to a population of around 1388 residents. Drakewalls is close to the city of Plymouth, which is approximately 10.8 miles away, and is also near the village of Albaston. Drakewalls is part of the wider South West region, and is around 190.7 miles from London.
Fuel drain cover across Cornwall, Drakewalls included
The teams answering petrol in diesel call-outs around Drakewalls, in the PL postcode area, equally work the locations around it, Higher Dimson, Dimson and Albaston included. Our technicians drain wherever the car is — your own drive, a lay-by, a supermarket car park, a forecourt — so it does not have to come to us.
In Drakewalls and still at the petrol pump?
Then you're in the best position there can be. Keep it off. Call.