Petrol in a Diesel Car in Overslade: How Worried Should You Be?
Provided it has not been started, worry less than you probably are. Until the ignition primes your pump, your starter cranks, or your car is driven, petrol in a diesel tank simply waits there and does nothing. Which means the honest reply to that first Overslade question — "have I ruined it?" — usually no. Petrol in Diesel is who to phone, with the motor kept off, so it remains that way. What petrol actually does to a diesel, how to judge how far it has gone, and how to keep it from happening a second time: that is the rest of this page.
What petrol in a diesel does to your engine
On its way through a motor, diesel has two tasks. It combusts, and before it burns it lubricates. Very fine clearances go into your injectors and your high-pressure pump, and only your diesel running through keeps their surfaces from grinding together.
The second task petrol does not do at all, and the first it does badly. It's runnier than diesel and strips away the protection your fuel system rests on, and so a pump running on a petrol mixture is a pump wearing itself. And petrol is designed to resist igniting under compression, which is the reverse of what a diesel needs from its fuel. That's where the rattling comes from.
The shape of the problem is clear once you put those together. The harm is done by movement, not by contact. Where that petrol is only inside that tank, it's an issue of fuel, nothing more. A pump that has been running on that petrol is the beginning of a mechanical one, and whatever a worn pump sheds travels on with the fuel to the injectors further on.
How bad is petrol in a diesel? Four scenarios our engineers see in Overslade
Filled up, and not started: nothing beats it. On a forecourt, and really only there, that petrol is still limited to that tank — since everywhere else the vehicle was driven to get to it. The task is draining and purging on the spot.
Started for a second, or only the ignition on. Your system has been bled, so petrol has left the tank and got to your filter and the fuel lines. Drain, flush, deal with the fuel filter: still usually easy.
Those few miles driven were the pump running on fuel thinned by petrol throughout. Tank, lines, filter, then fresh fuel run through the entire system: that is the work, and the way your car was driven counts as much as the miles. Short trips, like the school run to Rokeby Primary School, are one thing. Very different once more: a trip to Coventry, under 15 miles away, or any miles on the M45, under 3 miles from Overslade, where the engine never stopped labouring hard.
Knocking, an uneven idle, smoke, a throttle gone soft: driven until it complained. The motor is telling you your fuel is no longer acting like diesel. Pull up wherever you are — the verge on Overslade Manor Drive, a lay-by, a side street — then leave the vehicle there. What goes first is still the drain and flush-through, and that deals with it, with lasting damage very uncommon if a vehicle is stopped early.
Myths Overslade drivers hear about petrol in a diesel
Myth: "Fill it the rest of the way with diesel and it'll be fine." It will not. Topping up removes nothing; it gives you a bigger tank of the same mixture. The assumption behind the advice — that diesel fuel systems tolerate petrol by percentage — is wrong.
Myth: a newer diesel copes with a bit of petrol. If anything, the opposite. More precise components and higher pressure are the way a current diesel runs its fuel, and that makes the protection matter more, not less.
Myth: "If it starts and drives, there's no harm done." This is the one that catches drivers. Feed diesel to a petrol motor and it generally won't run, so the driver stops — and the damage stops with them. 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. Fine and running aren't the same thing.
An old workaround for a distinct fault lies behind this one. Myth: "Add some two-stroke oil and drive it home." None of what petrol thinned gets put back by it — and later, the tank still contains the petrol.
"Drain it yourself and you're sorted" — a myth, because after it's been running some petrol sits in the fuel filter and lines, ready to go right back through your pump on the next start. Besides, petrol cleared into a can by the road is genuinely dangerous.
Petrol in a diesel: how does it occur?
On purpose? Never. Through carelessness? Seldom, 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 car at all. The forecourt makes it easy, and the error runs one way.
It happens when routine and your car stop matching. Courtesy car, hire car, or a vehicle that's new. Households running one of each, petrol and diesel. A forecourt you know, only with its pumps laid out differently. A hurried fill on the way to Rugby with a train to catch. Exactly the moment it occurs: after years of driving petrol, a driver fills a diesel Volkswagen Golf 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.
Preventing petrol in a diesel next time you fill up in Overslade
- Check the petrol pump, not the colour. In the UK unleaded handles are usually green and diesel black, yet not on every forecourt. The label is what matters.
- Check your filler flap. Plenty of vehicles state the fuel type inside the flap or on the cap. Look at it on the first fill in any car you don't know.
- Good intentions do less than a sticker or a fob in a vivid colour on your diesel's key if a house has one of each. So label it.
- It seems 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.
- Tuck the phone away. This is an easy mistake to make whilst you are thinking about something else.
- Add-on devices exist for motors without one, and some diesels come with a filler that will not accept a petrol nozzle. Helpful — but a safety net at best, never a reason to stop checking the label.
- Stop as soon as you notice. Less petrol in your tank means a weaker mixture. It doesn't change what to do next, which is still not to start the car.
Put petrol in a diesel in Overslade already?
In that case, there is only a short order of things. Starting it is out, and so is switching on the ignition. Still on the forecourt, at Sainsburys or anywhere else? Ask the attendants to help you roll the vehicle clear of the petrol pump. Then call 0333 366 0103 and tell us what went in, about how much, and if it has run.
Corrosion and deposits form the issue with AdBlue, where petrol brings lost protection. So if it was AdBlue, say so — and see its own Overslade page.
One petrol in a diesel job around Overslade costs more than another. Why?
Four separate jobs sit behind the four situations above — which is why there is no honest single price. Chiefly, the cost moves with which one you're in. Two things come after that: the petrol that went in as a proportion of what your tank takes, then the place the vehicle is in and whether a technician can reach it safely.
That's why our technicians ask three queries before quoting instead of after: what got in, how much, and whether it's run. Their replies are what turn a range into one firm number.
About Overslade, briefly
Overslade is a suburban area in Warwickshire, situated near the River Avon and close to the cities of Coventry and Rugby. Overslade sits at an elevation of 118 metres, with semi-detached housing being the predominant type of accommodation in the area. Overslade is located near several nearby places, including Bilton, Rugby, and New Bilton, and is approximately 10.4 miles from Coventry. Overslade has a population of around 6521 residents.
Across Warwickshire and around Overslade: fuel drain cover
Bilton, Rugby and New Bilton are among the locations around Overslade that the same teams work, answering petrol in diesel call-outs across Overslade's CV postcode area. A forecourt, a supermarket car park, a lay-by or your own driveway are all spots we work, and your car does not need to move to us.
In Overslade and still at the petrol pump?
In that case, you couldn't be in a better spot. Keep it off. Phone.