Kingsand: Petrol in a Diesel Car? How Worried to Be
Far less than you probably are, if it hasn't been started. "Have I wrecked it?" is the first thing anyone in Kingsand asks, and the honest answer is normally no, since petrol resting in a diesel tank harms nothing until it's drawn through the system — by ignition priming, by your starter, or by being driven. To keep the vehicle like that, phone Petrol in Diesel and leave the engine alone. What petrol really does to a diesel, how to judge how far it has gone, and how to stop it from happening again: that's the rest of this page.
What petrol in a diesel does to the motor
Diesel does two jobs on its way through a motor. It burns, and before it combusts it protects. Built to extremely fine gaps, your injectors and the pump rely on the diesel flowing through them to keep their surfaces from wearing against one another.
Petrol handles the first job badly and the second not at all. Being less viscous than diesel, petrol strips away the lubrication a fuel system needs, leaving a pump on that mixture to wear itself. It is equally made to resist igniting under compression — the reverse of what a diesel needs — which is why you hear the rattling.
Together, those make the shape of the issue clear. The harm is done by movement, not by contact. Where the petrol is only in that tank, it is a problem of fuel, nothing more. 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 your fuel to the fuel injectors beyond it.
Kingsand, petrol in a diesel: four cases, from mild to significant
Fuelled but not once started — the best it gets. That petrol is inside the tank and just your tank, and the task is a drain and a flush where the vehicle stands. This is the one situation that can only really take place on a forecourt, since anywhere else the car has been driven to get there.
Ignition on, or started for a moment. Petrol has left the tank and got to your filter and your lines, because the system has been bled. Normally nothing more than clearing, rinsing and sorting your filter, so still easy.
Some miles driven, and your pump has spent each of them labouring on diluted fuel. Tank, lines, filter, then clean fuel run through the whole circuit: that is the work, and the way your car was driven matters as much as the mileage. Driving the children to Fourlanesend Community Primary School is one kind of trip. A run as far as Plymouth, under 5 miles away, is a very different task. So is any mileage on the M5, under 50 miles from Kingsand, where the engine has been running hard the whole time.
Driven until it protested. Knocking, a lumpy idle, smoke, a throttle that has gone soft. The fuel isn't behaving like diesel any more, and the motor is saying so. Pull up on the spot — on the verge on The Earl's Drive, at the kerb, down a side road — and do not move it again. What goes first is still the fuel drain and flush-through, and that sorts it out, with permanent damage very rare if a vehicle is pulled over soon.
Stories Kingsand drivers hear about petrol in a diesel
"Top it up the rest of the way with diesel and it will be fine" — a myth. It won't. Nothing comes out when you top up — your tank simply holds more of the same mixture. Percentage is not how a diesel fuel system copes with petrol, however much that advice presumes.
Myth: a modern diesel copes with a bit of petrol. If anything, the reverse. Protection matters more on newer diesels, not less, because their fuel runs through more precise components at higher pressure.
Myth: "If it starts and drives, there is no harm done." This is the one that fools motorists. The motorist of a petrol engine fed diesel normally stops, since it will not run, and the damage stops there. Nothing seems to have happened when a diesel fed petrol fires up, ticks over and drives away, which it usually does; meanwhile the pump grinds. Running doesn't mean fine.
Myth: "Add some two-stroke oil and drive the car home." It is an outdated fix for a different problem. That petrol is still in your tank afterwards, and whatever it has diluted isn't put back.
"Drain it yourself and you are sorted" — a myth, since after it has been running some petrol lies in the filter and lines, ready to go right back through your pump at your next start. It's also genuinely risky to drain petrol into a can at the kerbside.
How does petrol in a diesel happen?
On purpose? Never. Through carelessness? Rarely, if ever. The petrol nozzle is the slimmer of the two and slips into a diesel filler with almost no resistance; a diesel nozzle mostly will not go into a petrol vehicle at all. The forecourt makes it easy, and the error runs one way.
It happens when habit and the vehicle stop matching. Courtesy car, hire car, or a motor that's new. A household with one petrol and one diesel on the drive. A forecourt you know, only with its pumps arranged differently. A train to catch, and a hurried fill en route to Devonport. Years of petrol motors behind you, a diesel Renault Megane in front of you on the forecourt for its first tank — that's when. Throw in rain, a phone call or a back seat full of kids, and your hand does what it has always done.
Kingsand motorists: how to prevent petrol in a diesel next time
- Check the petrol pump, not the colour. In the UK unleaded handles are usually green and diesel black, but not on each forecourt. The label is what counts.
- Plenty of vehicles state the fuel type inside your filler flap or on the cap, so check it on your first fill in any car you do not know.
- Good intentions do less than a sticker or a fob in a bright colour on your diesel's key when a home has one of each. So mark it.
- 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 sounds daft and it does the trick.
- While you're thinking about something else, this is an easy mistake to make — so tuck your phone away.
- Some diesels have a filler built 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 safety net, not a reason to stop reading the pump.
- The moment you realise, stop: less petrol inside that tank means a thinner blend. What to do next doesn't change, though — still don't crank it.
Kingsand: already put petrol in a diesel?
In that case, there's just a short order of things. Don't turn the ignition on, and do not fire it up. Yet on the forecourt, at Esso or anywhere else? Ask the attendants to help you roll it clear of the petrol pump. What went in, about how much, and if it's run: tell us that when you ring 0333 366 0103.
Corrosion and deposits form the trouble with AdBlue, where petrol brings lost protection. So if it was AdBlue, say so — and see its own Kingsand page.
One petrol in a diesel task around Kingsand costs more than another. Why?
An honest single quote doesn't exist here: four scenarios, four separate jobs. Which of them you are in is chiefly what shifts your cost. Where your car is matters too, and whether a technician can safely get to it, after the proportion of petrol to what the tank holds.
Before any quote, not after, come three questions: your fuel that was put in, the volume, and if it's run. That is why. With those answers, you get a straight figure instead of a range.
About Kingsand itself
Kingsand is a small coastal village in Cornwall, situated near the Rame Peninsula and close to the neighbouring villages of Cawsand and Forder. Kingsand has a population of around 572 people and is characterized by its terraced housing. Kingsand sits at an elevation of 24 metres, overlooking the sea and offering views of the surrounding coastline. Kingsand is located approximately 3.6 miles from Plymouth, making it a popular residential area for those who work in the city.
Fuel drain cover in Kingsand and across Cornwall
The vans answering petrol in diesel jobs around Kingsand, in the PL postcode area, equally work the places near it, Cawsand, Forder and Rame included. The car does not need to come to us: our engineers drain at a forecourt, in a supermarket car park, in a lay-by or on your own driveway.
In Kingsand and still at the petrol pump?
The best place there is, then — that's where you are. Keep it off. Phone.