How Worried Should You Be? Petrol in a Diesel Car in Onley
Far less than you probably are, if it has not been started. "Have I wrecked it?" is the first thing anyone in Onley asks, and the honest answer is normally no, since petrol resting in a diesel tank hurts nothing until it's dragged through the system — by ignition priming, by your starter, or by being driven. Leave your motor off then call Petrol in Diesel — that keeps it that way. The rest of this page covers what petrol actually does to a diesel, how to tell how far it has got, and how to make sure it does not happen to you again.
Inside the engine: what petrol in a diesel really does
Two jobs fall to diesel on its journey round a motor. It lubricates first, and only then does it burn. Made to extremely fine clearances, the injectors and the pump rely on the diesel flowing through them to stop their surfaces wearing against one another.
Of those two tasks, petrol manages the first poorly and the second not at all. A pump running on a petrol blend is wearing itself out, since petrol is thinner than diesel and strips out the lubrication the fuel system relies on. Petrol is also designed to resist igniting under compression — the opposite of what a diesel needs from its fuel — and that is where the clattering starts.
Put these together and the shape of the trouble is plain. Not contact but movement is what does the harm. Petrol in the tank is a fuel fault. After your pump has been labouring on that petrol, a mechanical issue has begun: whatever is shed by a pump that is grinding travels downstream to the fuel injectors with the fuel.
Petrol in a diesel in Onley: how bad is it? Four cases
Fuelled up, never started. The best case there can be. At a forecourt, and really only there, that petrol is still limited to the tank — because everywhere else the car was driven to reach it. The job is draining and purging on the spot.
Your ignition turned on, or a short start. The fuel system has been bled, so petrol has left the tank and got to the filter and your lines. Drain, flush, deal with the filter: still usually straightforward.
Driven a few miles. Now your pump has spent these miles working on diluted fuel. The work is your tank, the fuel lines, your filter and clean fuel through the whole circuit, and how hard the vehicle was driven matters as much as how far. Short trips, such as the school run to Barby Church of England Primary School, are one thing. Driving as far as Coventry, under 15 miles away, makes a very different task — as does any mileage on the M45, under a mile from Onley, with the engine labouring hard all the way.
It protested, and only then stopped: smoke, rattling, a throttle gone soft, an idle gone ragged. The motor is telling you the fuel is no longer acting like diesel. Leave it where it has stopped: a lay-by, a side street, the verge on Onley Park. The drain and flush still come first, and they deal with it: if a car is pulled over early, long-term damage is very rare.
What Onley motorists get told about petrol in a diesel — and the myths in it
False: topping up to full with diesel makes it fine. It doesn't. Topping up takes out nothing; it gives you a fuller tank of the same mix. A diesel fuel system does not accept petrol by percentage in the way that guidance presumes.
If anything, the opposite is true. Myth: "A newer diesel can cope with a bit of petrol." More precise components and higher pressure are how a current diesel runs its fuel, and that makes the lubrication count more, not less.
Myth: "If it starts and drives, there's no harm done." This is the one that catches drivers. Diesel in a petrol motor usually means a motor that will not run: the motorist stops, and so does the damage. While the pump wears, a diesel fed petrol normally starts, ticks over and drives away as though nothing has happened. Running is not the same as fine.
Myth: "Add some two-stroke oil and drive the car home." It is an old fix for a different problem. That petrol is still inside that tank afterwards, and what it has weakened isn't put back.
"Drain it yourself and you're sorted" — a myth, since after it's been running some petrol sits in your filter and lines, waiting to go straight back through the pump on your next start. Besides, petrol emptied into a can by the road is genuinely hazardous.
Petrol in a diesel: how does it take place?
Nobody does it on purpose, and it is seldom carelessness. The forecourt makes it simple: the petrol nozzle is the narrower of the two, and it slips into a diesel filler with almost no resistance, whilst a diesel nozzle generally won't go into a petrol vehicle at all. So the error runs one way.
It occurs when routine and the vehicle stop matching. A new vehicle, a hire car or a courtesy car. A household with one petrol and one diesel on the driveway. The pumps in a different order on a well-known forecourt. A train to catch, and a hurried fill en route to Rugby. Years of petrol motors behind you, a diesel Volkswagen Golf in front of you on the forecourt for its first tank — that is when. Your hand does what it has always done when you add rain, a phone call or a back seat full of children.
Onley drivers: how to prevent petrol in a diesel next time
- Not every forecourt in the UK follows green for unleaded and black for diesel, though most generally do. Check the pump's label; the colour is just a hint.
- Inspect the filler flap. Plenty of motors state the fuel type inside the flap or on the cap. Look at it on the first fill in a vehicle you do not know.
- A coloured fob or a sticker on the diesel's key achieves more than any amount of meaning to remember, in a house with one of each.
- "Diesel", out loud, before you lift the nozzle — every time a new or hired car needs its first tank. It sounds silly. It does the trick.
- Thinking about something else is when this becomes an easy mistake to make, and so put your phone away then keep your mind on the petrol pump.
- A misfuel inhibitor helps, up to a point. Some diesels have 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 checking the pump.
- The moment you realise, stop: less petrol in your tank means a weaker blend. What to do next does not change, though — still do not fire it up.
Put petrol in a diesel around Onley already?
The order of things is brief, then. Starting it is out, and so is switching on your ignition. Ask the staff to help you push it away from the petrol pump if you're still at the forecourt, whether that is Sainsburys or anywhere else. Next, 0333 366 0103. We will ask what got in, about how much, and if it has been run.
AdBlue, not petrol? Then tell us. Corrosion and deposits, not lost protection, make it a separate problem — Onley has a page all for it.
What makes one Onley petrol in a diesel job cost more than the next
There's no fair single price for this, since the four scenarios above are four separate tasks. The situation itself does most of the work of moving the cost. Where the car is matters too, and whether a van can safely get to it, after the ratio of petrol to what the tank holds.
Three queries come first, before quoting, rather than after — what went in, how much, has it run — and that is the reason. Given those answers, you get a straight figure instead of a range.
About Onley itself
Onley is a village in Northamptonshire, situated on the riverside at an elevation of around 90 metres. Onley lies near the towns of Rugby and Daventry, and is close to the nearby villages of Woolscott, Barby, and Willoughby. Onley has a population of approximately 803 residents, with a predominance of semi-detached housing. Onley is located about 12 miles from Coventry and around 74 miles northwest of London.
Fuel drain cover across Northamptonshire, Onley included
Woolscott, Barby and Willoughby are among the locations near Onley that the same vans work, answering petrol in diesel call-outs across Onley's CV postcode area. The vehicle does not need to move to us: we drain on a forecourt, in a supermarket car park, in a lay-by or on your own drive.
At the petrol pump in Onley, still?
The best position there is, then — that is where you are. Call, and leave it turned off.