Kirkton: Petrol in a Diesel Car? How Worried to Be
Provided it has not been started, you can worry less than you likely are. Until your ignition primes your pump, your starter cranks, or your car is driven, petrol in a diesel tank just waits there and does no harm. Which means the honest reply to the first Kirkton question — "have I ruined it?" — normally no. Leave the motor off then phone Petrol in Diesel — that keeps it like that. What petrol really does to a diesel, how to judge how far it has travelled, and how to stop it from happening a second time: that is the remainder of this page.
Inside your engine: what petrol in a diesel does
Diesel has two tasks on its way through an engine. It ignites, and before it burns it protects. Designed to extremely fine clearances, the injectors and your pump depend on your diesel flowing through them to keep their surfaces from wearing against one another.
The second task petrol doesn't do at all, and the first it does badly. A pump working on a petrol mixture is wearing itself out, since petrol is runnier than diesel and strips out the protection the fuel system relies on. Petrol is also designed to resist igniting under compression — the reverse of what a diesel needs from its fuel — and that is where the knocking comes.
Seen together, they make clear what shape the trouble takes. Not contact but movement is what causes the harm. All a tank with petrol in it amounts to is a fuel fault. Whatever a worn pump sheds travels on, borne by your fuel, into the injectors downstream, which is why a pump that has been working on the petrol is where a mechanical problem starts.
Four scenarios we see in Kirkton: how bad is petrol in a diesel?
Fuelled, and not started: no case is better. At a forecourt, and really only there, the petrol is still limited to the tank — since anywhere else the car was driven to reach it. The task is emptying and cleaning on the spot.
Ignition on, or started for a moment. The system has been primed, so petrol has left that tank and got to your filter and the lines. Usually little more than clearing, rinsing and seeing to your filter, so still easy.
The pump has worked a couple of miles on weakened fuel — that's what driving it does. How hard your car was driven counts as much as how far, and the work takes in your tank, your lines, the filter and fresh fuel through the whole system. Short trips, such as the school run to the local primary school, are one matter. Any miles on the M8, under 3 miles from Kirkton, means the engine has worked hard throughout, and a run to Dunfermline, under 15 miles away, is a very different job as well.
It protested, and only then stopped: smoke, knocking, a throttle gone soft, an idle gone lumpy. That's your motor telling you its fuel has stopped behaving like diesel. Leave it where it stops: a lay-by, a side street, the verge on Lister Road. A vehicle pulled over early very seldom has permanent damage, since the drain and the flush, which still go first, take care of it.
Myths Kirkton people hear about petrol in a diesel
Myth: topping up to full with diesel makes it fine. It doesn't. Nothing is removed when you top up — that tank simply holds more of the same blend. Percentage is not how a diesel fuel system tolerates petrol, whatever that advice supposes.
"Modern diesels can handle a little petrol" — a myth, and nearer the reverse. At higher pressure, through finer components: that is how a current diesel moves its fuel, so the protection counts more, not less.
One myth that catches drivers off guard: if it starts and drives, it must be unharmed. The motorist of a petrol motor fed diesel normally has no choice but to stop, because it will not run, and the harm stops there. A diesel fed petrol generally starts, ticks over and drives away as though nothing has happened, while your pump wears. Fine and running aren't the same thing.
"A drop of two-stroke oil and drive it home" — a myth, borrowed from a fix from years ago, for a separate problem. It doesn't put back what petrol has weakened, and the petrol is still inside that tank later on.
"Drain it yourself and you're sorted" — a myth, since after it's been running some petrol sits in the fuel filter and lines, waiting to go right back through the pump at the next start. It's also truly hazardous to drain petrol into a can at the kerbside.
Why petrol in a diesel takes place at all
Nobody does it on purpose, and it is seldom carelessness. The petrol nozzle is the slimmer of the two and slides into a diesel filler with almost no resistance; a diesel nozzle generally won't go into a petrol car at all. The forecourt makes it simple, and the error runs one way.
Routine and your car getting out of step is when it takes place. Hire cars, courtesy cars, and cars that are new to you. A household with one petrol and one diesel on the drive. Your normal forecourt, its pumps suddenly in a different order. Racing for a train at Livingston North and filling up en route. Years of petrol motors behind you, a diesel Renault Clio in front of you at the forecourt for its first tank — that's when. With rain, a call arriving, or a car full of children to deal with, your hand just does what it always has.
Next time you fill up around Kirkton: avoiding petrol in a diesel
- The label is what matters, and so check the petrol pump rather than the colour: in the UK unleaded handles are normally green and diesel black, yet not on each forecourt.
- The first fill in a strange car is the time to check the filler flap — inside it, or on the cap, plenty of vehicles state the fuel they take.
- One of each in the household? Label the key to your diesel — a bright fob, a sticker — since meaning to remember isn't enough.
- "Diesel", out loud, before you lift the nozzle — every time a new or hired car needs its first tank. It sounds silly. It works.
- Whilst you're thinking about something else, this is an easy mistake to make — so put the phone away.
- Add-on devices are available for motors without one, and some diesels are built with a filler that will not accept a petrol nozzle. Helpful — but a backstop at best, never a reason to stop checking the label.
- Stop as soon as you notice. Less petrol inside that tank makes a weaker blend. It does not change what to do next, which is still not to fire it up.
Put petrol in a diesel around Kirkton already?
Then, there is only a short order of things. Do not switch the ignition on, and don't start it. The attendants on the forecourt — whether at Morrisons Daily itself or wherever you filled up — will usually help push it clear of the petrol pump if you ask. Call 0333 366 0103 next, with three facts — your fuel, the approximate volume, and whether it has run.
AdBlue, not petrol? Then tell us. Corrosion and deposits, not lost protection, make it a separate fault — Kirkton has a page all for it.
Kirkton petrol in a diesel tasks: why one costs more than another
Four separate tasks lie behind the four situations above — which is why there is no honest single quote. Chiefly, the cost moves with which situation you are in. Next it's the share — how much petrol went in against how much the tank takes — and after that where the car is and whether a technician can reach it safely.
That is why our technicians ask three queries before costing rather than after: what went in, how much, and if it's run. A range turns into a straight figure once the answers are in.
About Kirkton itself
Kirkton is a suburban area situated on the riverside in West Lothian, with a mix of detached housing and local amenities. Kirkton sits at an elevation of 119 metres, overlooking the surrounding countryside. Kirkton is located near several nearby places, including Livingston Village and Kirton Campus, and is within commuting distance of Dunfermline. Kirkton remains a residential community with a population of around 1619 people.
Kirkton and West Lothian: where our fuel drain cover reaches
Petrol in diesel calls in Kirkton — part of the EH postcode area — go to vans that likewise cover the locations about it, Livingston Village, Kirton Campus and Adambrae included. The car does not 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.
In Kirkton and still at the petrol pump?
Then, you could not be in a better place. Keep it off. Phone.