How Worried Should You Be? Petrol in a Diesel Car in Lelant
Far less than you probably are, provided it has not been started. Till the ignition primes the pump, the starter cranks, or your vehicle is driven, petrol in a diesel tank simply waits there and does nothing. Which makes the truthful reply to that first Lelant query — "have I wrecked it?" — usually no. Leave the motor off then ring Petrol in Diesel — that is how you keep it like that. Read on for three things: the effect petrol has inside a diesel engine, the clues of how far it has spread, and ways to make sure you don't do it again.
The engine and petrol in a diesel: what happens
On its way through a motor, diesel does two jobs. Oiling comes before burning; it does both. Very fine gaps go into your injectors and your high-pressure pump, and just your diesel running through stops those surfaces grinding together.
Of those two jobs, petrol manages the first poorly and the second never. The knocking comes from petrol being designed not to ignite when compressed, which is exactly the reverse of what a diesel needs. On top of that it is runnier than diesel, it strips out the lubrication your system hinges on, and any pump running on such a mixture is wearing itself.
Seen together, they show what shape the trouble has. Not contact but movement is what causes the damage. Where the petrol is only in your tank, it is a problem of fuel, nothing more. Whatever a worn pump sheds goes on, borne by your fuel, into the fuel injectors further along, which is why a pump that has been working on the petrol is where a mechanical fault begins.
How serious is petrol in a diesel? Four scenarios our engineers see in Lelant
Fuelled up, never started. The best case there is. At a forecourt, and really only there, that petrol is still limited to that tank — since everywhere else the vehicle was driven to reach it. The job is emptying and rinsing on the spot.
A brief spell of running, or just your ignition on. Once primed, your system has drawn petrol out of your tank as far as your filter and your lines. Still generally easy: drain, flush, and your filter sorted.
Your pump has worked a couple of miles on diluted fuel — that's what driving the vehicle meant. How hard the car was driven matters as much as how far, and this work covers the tank, the lines, the filter and fresh fuel through the entire system. Driving the children to Penpol School is one kind of trip. Very different again: a trip to Truro, under 25 miles away, or any distance on the M5, over 50 miles from Lelant, where your engine kept working hard.
Driven until it protested. Rattling, a ragged idle, smoke, a throttle that has gone soft. The motor is telling you the fuel is no longer acting like diesel. Leave it wherever it stops: a lay-by, a quiet street, the verge on Tyringham Road. The drain and flush-through still come first, and they deal with it: when a car is stopped quickly, long-term damage is very unusual.
Lelant 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 will be." A bigger tank of the same mix is all it gives, since topping up takes out nothing. A diesel fuel system does not accept petrol by percentage in the way that guidance assumes.
"Newer diesels can handle a little petrol" — a myth, and closer to the opposite. At higher pressure, through finer parts: that's how a modern diesel moves its fuel, and so the lubrication matters more, not less.
This is the one that fools drivers. Myth: "If it starts and drives, there is no harm done." Feed diesel to a petrol engine and it normally won't run, and so the driver stops — and the harm stops with them. A diesel fed petrol usually starts, idles and drives away as if nothing has happened, whilst the pump wears. Fine and running are not the same thing.
An old fix for a separate issue lies behind this one. Myth: "Add some two-stroke oil and drive it home." It doesn't put back what petrol has diluted, and that petrol is still inside your tank later on.
"Drain it yourself and you are sorted" — a myth, because after it's been running some petrol sits in your filter and lines, ready to go right back through the pump at your next start. Besides, petrol emptied into a can by the road is truly risky.
Why petrol in a diesel takes place so easily
Carelessness is rarely the cause, and nobody means to do it. The forecourt makes it simple: the petrol nozzle is the smaller of the two, and it slips into a diesel filler with almost no resistance, while a diesel nozzle mostly will not go into a petrol vehicle at all. So the error runs one way.
When habit and your car stop matching, it occurs. Hire cars, courtesy cars, and cars that are new to you. Households running one of each, petrol and diesel. The pumps in a different order on a familiar forecourt. Fuelling up in a hurry on the way to the nearest station, with a train to catch. Exactly the moment it occurs: after years of driving petrol, a driver fills a diesel Volkswagen Passat for the first time. The hand does what it has always done when you add rain, a phone call or a back seat full of kids.
Next time you fill up in Lelant: avoiding petrol in a diesel
- Not every forecourt in the UK follows green for unleaded and black for diesel, even if most generally do. Check the petrol pump's label; the colour is only a hint.
- In a motor you don't know, look inside the flap over your filler or at the cap before the first fill: plenty of cars state the fuel there.
- Mark your key. In a house with one of each, a coloured fob or a sticker on your diesel's key does more than any amount of meaning to remember.
- Before the nozzle leaves the petrol pump the first time you fuel a hired or new motor, say "diesel" out loud. Daft, yes, but it does the trick.
- Whilst you're thinking about something else, this is an easy mistake to make — so put your phone away.
- Add-on devices exist for cars without one, and some diesels come with a filler that will not take a petrol nozzle. Useful — but a safety net at best, never a reason to stop checking the label.
- Stop the moment you notice. Less petrol in that tank means a thinner mix. It does not change what to do next, which is still not to start it.
Put petrol in a diesel around Lelant already?
The order of things is short, then. Never start the car, and do not switch the ignition on. Ask the attendants to help you push it away from the pump if you are still on the forecourt, whether that is Central Garage or anywhere else. Then ring 0333 366 0103 and tell us what was put in, about how much, and if it has run.
If it was AdBlue rather than petrol, say so. That's a different issue — corrosion and deposits and not lost lubrication — and it has its own page for Lelant.
One petrol in a diesel task around Lelant costs more than another. Why?
Four different tasks sit behind the four scenarios above — which is why there is no fair single quote. Mostly, the cost moves with which situation you are in. The ratio matters next, meaning how much of the tank is petrol, and then the location of the car and whether getting to it is safe for a van.
What was put in, how much, and if it's run — three questions our engineers ask before costing, not after, for precisely that reason. Those answers change a range into a straight figure.
About Lelant
Lelant is a small coastal village in Cornwall, situated near the mouth of the Hayle Estuary at an elevation of 31 metres. Lelant lies within a short distance of nearby settlements such as Griggs, Hayle, and Foundry, and is approximately 18 miles from the city of Truro. Lelant has a population of around 596 people, predominantly living in detached housing. Lelant is located in the South West region of England, about 249 miles from London.
Fuel drain cover in Lelant and across Cornwall
Griggs, Hayle and Foundry are among the locations near Lelant that the same vans work, answering petrol in diesel calls across Lelant's TR postcode area. The vehicle doesn't need to move to us: our technicians drain on a forecourt, in a supermarket car park, in a lay-by or on your own drive.
Lelant: still at the pump?
In that case, you could not be in a better place. Keep the car turned off, then ring.