Wisbech: Petrol in a Diesel Car? How Worried to Be
Far less than you probably are, if it hasn't been started. "Have I ruined it?" is the first question anyone in Wisbech asks, and the truthful answer is usually no, because petrol resting in a diesel tank hurts nothing until it is drawn through the system — by ignition priming, by your starter, or by driving. Petrol in Diesel is who to phone, with the motor left off, and so it stays that way. Further down, you will find what petrol really does inside a diesel, how far it might have got, and how to stop it happening to you again.
Inside the engine: what petrol in a diesel does
Diesel does two tasks on its way through an engine. It lubricates to begin with, and after that does it burn. Built to very fine clearances, the fuel injectors and your pump depend on the diesel flowing through them to keep their surfaces from wearing against one another.
Badly at the first, not at all at the second: that is petrol. Being less viscous than diesel, petrol strips away the protection a fuel system needs, so a pump on the blend to wear itself. It is also made to resist igniting under compression — the opposite of what a diesel needs — which is where you get the rattling.
Seen together, they show what shape the problem has. Contact does not do the harm — movement does. Any tank with petrol in it is a fuel fault. After your pump has been working on that petrol, a mechanical problem has started: anything shed by a pump that is wearing travels onward to the fuel injectors with your fuel.
Petrol in a diesel around Wisbech: how bad is it? Four cases
Fuelled but never started — as good as it gets. Being at a forecourt is what makes this the case: elsewhere, the vehicle has been driven there to begin with. With that petrol held in that tank alone, it's emptied and flushed right where it stands, and nothing more is needed.
The ignition turned on, or a short start. Once primed, the system has drawn petrol out of your tank as far as the fuel filter and the lines. Still usually simple: drain, flush, and your filter dealt with.
The pump now worked a couple of miles on thinned fuel — that is what driving it meant. Tank, lines, filter, then fresh fuel run through the entire circuit: that is this work, and the way your car was driven matters as much as the miles. The school run to The Nene Infant & Nursery School is one thing. A run as far as Peterborough, under 25 miles away, is a very different task. So is any mileage on the A1(M), under 25 miles from Wisbech, where the motor has been working hard the whole time.
Driven till it complained. Rattling, a lumpy idle, smoke, a throttle that has gone soft. That's the motor telling you its fuel has stopped acting like diesel. Pull up wherever you are — the verge on Church Terrace, a lay-by, a side street — and leave the vehicle where it is. What goes first is still the drain and flush, and that deals with it, with permanent damage very rare if a car is stopped soon.
Myths Wisbech motorists hear about petrol in a diesel
Myth: "Fill it the rest of the way with diesel and it will be fine." It will not. A bigger tank of the same mix is all it gives, since topping up takes out nothing. The assumption behind that advice — that diesel fuel systems tolerate petrol by percentage — is wrong.
"Modern diesels can handle a little petrol" — a myth, and closer to the opposite. Finer components and higher pressure are the way a current diesel runs its fuel, and that makes the lubrication matter more, not less.
Myth: "If it starts and drives, there's no damage done." This is the one that fools people. The motorist of a petrol motor fed diesel usually stops, because it will not run, and the harm stops there. Whilst your pump wears, a diesel fed petrol normally starts, ticks over and drives away as though nothing has happened. Running is not the same as fine.
An outdated workaround for a separate issue lies behind this one. Myth: "Add some two-stroke oil and drive the car home." It does not put back what petrol has thinned, and the petrol is still inside that tank later on.
"Drain it yourself and you are sorted" — a myth, since after it has been running some petrol sits in the filter and lines, ready to go right back through your pump at the next start. It is also really risky 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's rarely carelessness. The petrol nozzle is the narrower of the two and slides 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 slip runs one way.
It happens when routine and the car stop matching. Courtesy car, hire car, or a vehicle that is new. One petrol and one diesel on the drive of the same household. Your normal forecourt, its pumps now in a different order. Filling up in a hurry on the way to March, with a train to catch. A new-to-you diesel Renault Megane, its first fuelling, and a motorist used to petrol: precisely when it takes place. Throw in rain, a phone call or a back seat full of children, and your hand does what it has always done.
Next time you fill up in Wisbech: avoiding petrol in a diesel
- A green handle for unleaded and black for diesel is normal in the UK — but not on each forecourt. Go by the label on the pump, not the colour.
- Many cars state the fuel type inside the filler flap or on the cap, so check there on the first fill in a vehicle you don't know.
- 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 intending to remember.
- It seems daft and it does the trick: on your first fill in a new or hired car, say "diesel" out loud before you take the nozzle off the pump.
- Put your phone away. This is an easy mistake to make while you are thinking about something else.
- Add-on devices exist for cars without one, and some diesels are built with a filler that will not take a petrol nozzle. Helpful — but a safety net only, never a reason to stop checking the label.
- Stop as soon as you realise. Less petrol inside that tank makes a thinner mixture. It doesn't change what to do next, which is still not to fire it up.
Petrol already in a diesel around Wisbech? Start here
Then the order of things is brief. Do not fire it up, and do not switch your ignition on. Yet on the forecourt, at BP or anywhere else? Ask the staff to help you roll it away from the pump. What got in, about how much, and whether it has run: tell us those when you ring 0333 366 0103.
If it was AdBlue and not petrol, say so. That's a separate fault — corrosion and deposits and not lost lubrication — and it has its own page for Wisbech.
One petrol in a diesel job around Wisbech costs more than another. Why?
An honest single quote does not exist here: four scenarios, four separate jobs. Which of them you're in is chiefly what shifts the cost. The proportion counts next, meaning how much of the tank is petrol, followed by the position of the vehicle and whether getting to it is safe for a van.
Before any quote, not after, come three queries: your fuel that got in, its quantity, and if it has run. That's why. The replies change a range into a straight figure.
About Wisbech, for a moment
Wisbech is a town situated in a riverside location in the north-east of Cambridgeshire, near the borders with Norfolk and Lincolnshire. It is known for its historic significance as a port and market centre. The town's landscape is characterised by the River Nene, which flows through it and is crossed by road bridges. Wisbech is a notable settlement in the Fenland region, often referred to as a key hub in the area.
Across Cambridgeshire and around Wisbech: fuel drain cover
Petrol in diesel call-outs around Wisbech — part of the PE postcode area — go to teams that likewise cover the spots round it, Great Boleness Field, Walsoken and Paradise included. The vehicle does not need to move to us: our engineers drain on a forecourt, in a supermarket car park, in a lay-by or on your own drive.
Still at the pump around Wisbech?
The best spot there is, then — that's where you are. Keep it off. Phone.