Laceby: Petrol in a Diesel Car? How Worried to Be
Likely less than you are now — provided no one has started it. "Have I wrecked it?" is the first thing everyone in Laceby asks, and the truthful answer is normally no, because petrol resting in a diesel tank harms nothing till it is dragged through your fuel system — by ignition priming, by your starter, or by driving. Leave the motor off and phone Petrol in Diesel — that is how you keep it like that. The remainder of this page explains what petrol actually does to a diesel, how to judge how far it has got, and how to make sure it doesn't happen to you again.
Petrol in a diesel: what does it do to the motor?
On its way through a motor, diesel does two tasks. Before it combusts, it protects — and then it ignites. What keeps the surfaces inside your high-pressure pump and the fuel injectors from grinding against one another is your diesel flowing through them — they're built to extremely fine tolerances.
Badly at the first, not at all at the second: that's petrol. The knocking comes from petrol being designed not to ignite when compressed, which is precisely the opposite of what a diesel needs. On top of that it is runnier than diesel, it strips away the lubrication the fuel system rests on, and any pump working on such a blend is wearing itself.
Put those together and the shape of the problem is plain. It is circulation that causes the damage, not contact. Petrol in the tank is a fuel problem. 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 injectors downstream.
Four scenarios we see around Laceby: how bad is petrol in a diesel?
Filled up, not once started. The best case there can be. The petrol is inside the tank and just the tank, and the job is a drain and a flush where the vehicle sits. This is the one scenario that can only really happen on a forecourt, as anywhere else the car has been driven to get there.
Started for a moment, or just your ignition on. Petrol has left your tank and got to the filter and the lines, because your system has been primed. Drain, flush, deal with the fuel filter: still usually easy.
A couple of miles driven, and your pump has spent each of them running on thinned fuel. How hard the car was driven counts as much as how far, and this work takes in that tank, the lines, the filter and fresh fuel through the whole circuit. On the school run to Laceby Stanford Primary Academy, the mileage is small. Driving as far as Kingston upon Hull, under 25 miles away, makes a very different task — as does any distance on the M180, under 15 miles from Laceby, with the engine running hard the whole time.
Clattering, a lumpy idle, smoke, a throttle gone soft: driven until it complained. The fuel isn't acting like diesel any more, and the engine is saying so. Pull up wherever you are — the verge on Cemetery Road, a lay-by, a side street — and leave it there. What comes first is still the fuel drain and flush, and that deals with it, with long-term damage very rare when a car is stopped quickly.
Petrol in a diesel stories Laceby motorists hear
Myth: "Fill it the rest of the way with diesel and it will be fine." It will not. Nothing is removed by topping up — you're left with a bigger tank, still the same mix. That advice supposes a diesel fuel system tolerates petrol by percentage. It does not.
Myth: "A current diesel can cope with a bit of petrol." If anything, the opposite. Lubrication matters more on newer diesels, not less, because their fuel runs through more precise components at higher pressure.
This is the one that catches motorists. Myth: "If it starts and drives, there is no harm done." Any petrol engine fed diesel normally won't run, so the driver stops and the harm stops with them. Feed petrol to a diesel and it generally starts, idles and drives away as if nothing happened — all the while its pump wears. Being able to run is not proof of being fine.
Not so: a two-stroke additive makes it safe to drive home. It was an old workaround, meant for another problem. It doesn't put back what petrol has diluted, and the petrol is still inside the tank afterwards.
Myth: "Drain that tank yourself and you are sorted." After your engine has run, some of the petrol is no longer in the tank: it is in your filter and your lines, and it goes right back through your pump at your next start. Also, a can of petrol drained by the kerbside is truly hazardous.
How does petrol in a diesel occur?
It's seldom carelessness, and nobody does it on purpose. The petrol nozzle is the slimmer of the two and slips into a diesel filler with almost no resistance; a diesel nozzle mostly won't go into a petrol vehicle at all. The forecourt makes it simple, and the error runs one way.
Routine and the car getting out of step is how it happens. A car that's new to you — a hire car, on loan as a courtesy car, or brand new. Households running one of each, petrol and diesel. Your usual forecourt, its pumps suddenly in a different order. Fuelling up in a rush en route to Healing, with a train to catch. Precisely the moment it happens: after years of driving petrol, someone fills a diesel Volkswagen Golf for the first time. Add a back seat full of children, a phone call or rain, and habit takes over.
Avoiding petrol in a diesel next time you fill up around Laceby
- Green for unleaded and black for diesel is usual in the UK — yet not on every forecourt. Go by the label on the pump, not the colour.
- The first fill in a new motor is the time to check the filler flap — on it, or on the cap, many cars state the fuel they take.
- Good intentions do less than a sticker or a fob in a bright colour on the diesel's key when a house has one of each. So mark it.
- It seems silly and it works: on the first fill in a new or hired car, say "diesel" out loud before you lift the nozzle off the petrol pump.
- Tuck the phone away. This is an easy mistake to make while you're thinking about something else.
- Add-on devices exist for motors 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 as soon as you realise. Less petrol in your tank makes a thinner mix. It doesn't change what to do next, which is still not to start the vehicle.
Already put petrol in a diesel in Laceby?
Then the order of things is brief. Starting it is out, and so is switching on your ignition. If you're still on the forecourt — Shell or anywhere else — ask the attendants to help you roll the car clear of the petrol pump. What got in, roughly how much, and whether it's run: tell us that when you phone 0333 366 0103.
If it was AdBlue and not petrol, say so. That is a different fault — corrosion and deposits rather than lost lubrication — and it has its own page for Laceby.
Laceby petrol in a diesel jobs: why one costs more than another
The four situations above are four separate jobs, so no single price for this would be honest. Chiefly, your cost moves with which situation you're in. Next it's the proportion — how much petrol went in against how much that tank takes — and then where the car is and whether a technician can get to it safely.
That's why we ask three queries before quoting instead of after: what was put in, how much, and if it's run. The replies change a range into a straight figure.
About Laceby
Laceby is a village situated on the banks of a river in Lincolnshire, with an elevation of around 17 metres above sea level. Laceby lies approximately 15 miles from Kingston upon Hull and 140 miles from London, making it a relatively accessible rural community. Laceby has a mix of housing types, but semi-detached homes are particularly prevalent in the area. Laceby is surrounded by other small settlements, including Aylesby and Irby upon Humber.
Laceby and Lincolnshire: where our fuel drain cover runs
Petrol in diesel jobs around Laceby — part of the DN postcode area — go to vans that likewise cover the locations around it, Aylesby, Irby upon Humber and Laceby Acres among them. You need not bring your vehicle to us. Forecourts, supermarket car parks, lay-bys and your own driveway are all locations where we work.
Still at the petrol pump in Laceby?
The best spot there is, then — that's where you are. Phone, and keep it switched off.