Addington: Petrol in a Diesel Car? How Worried to Be
Likely less than you already are — as long as nobody has started the vehicle. Till the ignition primes your pump, your starter cranks, or your vehicle is driven, petrol in a diesel tank just waits there and does no harm. Which makes the honest reply to that first Addington question — "have I ruined it?" — normally no. Keep it that way: leave the motor off and ring Petrol in Diesel. Further down, you will find what petrol actually does inside a diesel, how far it may have got, and how to stop it happening to you a second time.
Your engine and petrol in a diesel: what goes on
Diesel has two jobs on its way through a motor. Lubricating comes before burning; it does both. Your high-pressure pump and your injectors are built to extremely fine tolerances, and your diesel passing through them is what stops those surfaces from wearing down against each other.
Poorly at the first, not at all at the second: that is petrol. Being less viscous than diesel, petrol strips out the protection a fuel system needs, so a pump on the blend to wear itself. It's equally made to resist igniting under compression — the reverse of what a diesel needs — which is where you hear the rattling.
Together, those leave the shape of the trouble clear. Contact doesn't do the damage — circulation does. A tank with petrol in it is a fuel fault. After your pump has been labouring on that petrol, a mechanical issue has begun: anything shed by a pump that is grinding is carried downstream to the fuel injectors with your fuel.
How serious is petrol in a diesel? Four situations our engineers see around Addington
The best case there is: filled up, not once started. On a forecourt, and really only there, the petrol is still limited to your tank — because everywhere else the vehicle was driven to reach it. The job is draining and cleaning on the spot.
The ignition turned on, or a brief start. The fuel system has been primed, and so petrol has left your tank and got to the fuel filter and the lines. Still usually simple: drain, flush, and the fuel filter dealt with.
Those few miles on the road were the pump running on fuel diluted by petrol throughout. How hard the vehicle was driven matters as much as how far, and this work takes in that tank, the lines, the fuel filter and fresh fuel through the whole circuit. Short trips, like the school run to St Martin's CofE Primary School, are one thing. Very different again: a trip to Plymouth, under 25 miles away, or any miles on the M5, under 50 miles from Addington, where the motor never stopped working hard.
Driven until it protested. Knocking, a lumpy idle, smoke, a throttle that has gone soft. The motor is telling you the fuel is no longer acting like diesel. Stop wherever you are — the verge on Miners Way, a lay-by, a side street — and leave the car where it is. A car stopped soon very seldom has lasting damage, since the fuel drain and the flush-through, which still go first, take care of it.
Myths Addington 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 are left with a bigger tank, still the same mix. The idea behind the guidance — that diesel fuel systems accept petrol by percentage — is wrong.
If anything, the reverse is true. Myth: "A newer diesel can cope with a bit of petrol." Lubrication matters more on modern diesels, not less, since their fuel passes through smaller components at higher pressure.
"It starts, it drives, so no harm done" — the myth that catches most drivers than any other. Diesel in a petrol motor generally means a motor that won't run: the motorist stops, and so does the damage. A diesel fed petrol generally starts, ticks over and drives away as though nothing has happened, while your pump wears. Running does not mean fine.
"A drop of two-stroke oil and drive it home" — a myth, borrowed from a fix from years ago, for a distinct problem. What petrol has weakened remains diluted, and that petrol stays in that tank regardless.
The next start sends petrol back round the pump out of the lines and the filter, where some of it sits after your engine has run. That's why draining the tank yourself doesn't leave you sorted — a myth. Besides, petrol cleared into a can by the road is genuinely dangerous.
Why petrol in a diesel happens so easily
It's rarely carelessness, and nobody does it on purpose. A diesel nozzle generally will not fit a petrol vehicle, yet the smaller petrol nozzle goes into the filler of a diesel nearly without resistance — so forecourts make this one error straightforward, and just in one direction.
When habit and the car stop matching, it occurs. A new car, a hire car or a courtesy car. Two vehicles on one drive, one petrol, one diesel. A forecourt you know, only with its pumps laid out differently. Fuelling up in a hurry en route to Liskeard, with a train to catch. Exactly the moment it occurs: after years of driving petrol, a driver fills a diesel BMW 3 Series for the first time. With rain, a call arriving, or a car full of children to deal with, the hand simply does what it has always done.
Addington drivers: how to avoid petrol in a diesel next time
- Green for unleaded and black for diesel is normal in the UK — but not on every forecourt. Go by the label on the pump, not the colour.
- In a motor you don't know, look inside the flap over your filler or at the cap before the first fill: many cars state the fuel there.
- One of each in the home? Label the key to your diesel — a bright fob, a sticker — because meaning to remember isn't enough.
- Say it before you lift it. On your first fill in a new or hired car, say "diesel" aloud before you lift the nozzle off the pump. It seems silly and it works.
- Mistakes like this are straightforward to make whilst your mind is on something else, so the phone goes away.
- Some diesels come with a filler designed to reject a petrol nozzle, and devices you can add exist for cars without one. Such an inhibitor helps up to a point — as a backstop, not a reason to stop reading the petrol pump.
- As soon as you realise, stop: less petrol inside that tank means a thinner mixture. What to do next doesn't change, though — still don't fire it up.
Addington: already put petrol in a diesel?
Then the order of things is short. Don't turn the ignition on, and don't fire it up. The staff at the forecourt — whether at BP itself or wherever you filled up — will normally help push it away from the petrol pump if you ask. Next, 0333 366 0103. We will ask what went in, about how much, and if it's been run.
Corrosion and deposits form the trouble with AdBlue, where petrol brings lost protection. So if it was AdBlue, say so — and read its own Addington page.
One petrol in a diesel job around Addington costs more than another. Why?
Four different tasks sit behind the four scenarios above — which is why there is no honest single price. The scenario itself does most of the work of moving your cost. Two things come after that: the petrol that was put in as a share of what your tank holds, then the spot your car is in and whether our van can get to it safely.
Three questions come first, before any quote, rather than after — what got in, how much, has it run — and this is the reason. Given those answers, there is a straight figure instead of a range.
About Addington and where it is
Addington is a suburban area situated on the riverside in Cornwall, with a mix of terraced housing and a population of around 5012 residents. Addington sits at an elevation of 145 metres, near the towns of Liskeard and Trembraze, and is approximately 15 miles from Plymouth. Addington forms part of the wider suburban landscape around Plymouth, with Hendrabridge nearby. Addington is located in the South West region of England, about 201 miles from London.
Across Cornwall and in Addington: fuel drain cover
Petrol in diesel calls around Addington — part of the PL postcode area — go to teams that likewise cover the spots around it, Trembraze, Liskeard and Hendrabridge among them. A forecourt, a supermarket car park, a lay-by or your own driveway are all spots we drain, and your car doesn't need to move to us.
Still at the petrol pump around Addington?
Nothing beats it: that's where you now are. Leave the vehicle switched off, then ring.