Portsea: Petrol in a Diesel Car? How Worried to Be
If it hasn't been started, worry less than you likely are. Everyone in Portsea starts with "have I wrecked it?", and the fair answer is normally no: petrol resting in the tank of a diesel remains harmless until priming, cranking or driving pulls it into your fuel system. Leave your motor off then phone Petrol in Diesel — that is how you keep it that way. The rest of this page explains what petrol really does to a diesel, how to judge how far it has got, and how to make sure it does not happen to you again.
What petrol in a diesel does to the engine
Two tasks fall to diesel on its route through a motor. It lubricates first, and only then does it burn. Designed to extremely fine tolerances, the injectors and your pump rely on the diesel flowing through them to stop their surfaces wearing against one another.
Petrol does the first job poorly and the second not at all. Being less viscous than diesel, petrol strips away the protection a fuel system needs, leaving a pump running on the mixture wearing itself. It's also made to resist igniting under compression — the opposite of what a diesel needs — which is why you hear the rattling.
The shape of the problem is plain once you put those together. It's circulation that does the harm, not contact. Any tank with petrol in it is a fuel problem. After your pump has been working on that petrol, a mechanical fault has started: anything shed by a pump that's grinding is carried downstream to the injectors with the fuel.
Petrol in a diesel around Portsea: how serious is it? Four situations
Filled but not once started — the best it gets. Just that tank has petrol in it, and so the task is emptying the tank and rinsing the system where the vehicle stands. This scenario can only really take place at a forecourt: anywhere else, the car got there by being driven.
A moment's running, or merely the ignition on. With the fuel system primed, the fuel lines and filter already contain petrol that came from that tank. That's generally still an easy job — a drain, a flush, and the fuel filter seen to.
Your pump now spent a few miles on diluted fuel — that's what driving the car does. Distance is only half of it; how hard it was driven counts equally. Either way the work includes that tank, the lines, the filter and clean fuel through the entire circuit. Short trips, such as the school run to St George's Beneficial Church of England (Voluntary Controlled) Primary School, are one matter. Very different once more: a run to Portsmouth, under a mile away, or any mileage on the M275, under a mile from Portsea, where the engine never stopped running hard.
Driven until it protested. Rattling, an uneven idle, smoke, a throttle that has gone soft. The fuel is not behaving like diesel any more, and your motor is saying so. Pull up wherever you are — the verge on Bishop Street, a lay-by, a side street — and leave it where it is. The drain and flush-through still go first, and they deal with it: when a car is pulled over early, long-term damage is very rare.
What Portsea drivers get told about petrol in a diesel — and the myths in it
Myth: "Fill it the rest of the way with diesel and it will be fine." It will not. A fuller tank of the same mix is all you get, since topping up removes nothing. The assumption behind that guidance — that diesel fuel systems accept petrol by percentage — is wrong.
"Newer diesels can handle a little petrol" — a myth, and closer to the opposite. Smaller parts and higher pressure are the way a current diesel runs its fuel, and that makes the lubrication count more, not less.
This is the one that fools motorists. Myth: "If it starts and drives, there is no damage done." Diesel in a petrol motor usually means a motor that won't run: the driver stops, and so does the harm. Feed petrol to a diesel and it normally starts, ticks over and drives away like nothing has happened — all the while its pump is wearing. Running doesn't mean fine.
Myth: "Add some two-stroke oil and drive it home." It is an outdated fix for a different issue. It doesn't put back what petrol has diluted, and the petrol is still inside that tank later.
Myth: "Drain that tank yourself and you're sorted." After your engine has been run, some of that petrol is no longer in the tank: it's in your filter and your lines, and it goes right back through your pump at the next start. Besides, petrol drained into a can by the road is genuinely dangerous.
How it happens: petrol in a diesel
It is rarely carelessness, and nobody does it on purpose. The forecourt makes it easy: the petrol nozzle is the smaller of the two, and it slips into a diesel filler with almost no resistance, while a diesel nozzle mostly will not go into a petrol vehicle at all. So the mistake runs one way.
The moment routine stops matching the car is the moment it takes place. A motor that is new to you — hired, on loan as a courtesy car, or just bought. One petrol and one diesel on the drive of the same household. A forecourt you know, but with its pumps arranged differently. A train to catch, and a rushed fill on the way to Portsmouth Harbour. Exactly the moment it happens: after years of driving petrol, a driver fills a diesel Volkswagen Passat for the first time. The hand does what it has always done when you add rain, a phone call or a back seat full of children.
Avoiding petrol in a diesel next time you fill up in Portsea
- Green for unleaded and black for diesel is usual in the UK — yet not on every forecourt. Trust the label on the pump, not the colour.
- The first fill in a strange motor is the time to check your filler flap — inside it, or on the cap, many motors state which fuel to use.
- Good intentions do less than a sticker or a fob in a bright colour on the diesel's key if a house has one of each. So label it.
- "Diesel", out loud, before you pick up the nozzle — each time a new or hired car gets its first tank. It seems daft. It does the trick.
- Put your phone away. This is an easy mistake to make whilst you are thinking about something else.
- A misfuel inhibitor helps, up to a point. Some diesels have a filler designed to block a petrol nozzle, and add-on devices are available for cars without one. They are a safety net, not a reason to stop checking the pump.
- Spotting it halfway? Stop at once. A weaker mixture follows from less petrol in the tank, yet your next stage stays the same: do not start it.
Portsea: already put petrol in a diesel?
In that case, there is only a short order of things. Leave it unstarted, with the ignition switched off too. Ask the attendants to help you push it away from the petrol pump if you're still on the forecourt, whether that is BP or anywhere else. Then call 0333 366 0103 and tell us what got in, about how much, and whether it's 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 Portsea page.
Why one petrol in a diesel job around Portsea costs more than another
An honest single quote doesn't exist here: four situations, four separate jobs. Mostly, your cost shifts with which one you are in. Beyond that it's the ratio — how much petrol went in against how much your tank holds — and after that where your car is and whether a technician can get to it safely.
That's why we ask three queries before costing rather than after: what was put in, how much, and if it has run. Those replies are what change a range into one firm number.
About Portsea
Portsea is a suburban area located on the coast of Hampshire, situated close to the city of Portsmouth. Portsea sits at a low elevation of around 9 metres, with its predominant housing stock consisting of flats. Portsea is part of the larger Portsmouth urban area, with nearby places including Somers Town and Old Portsmouth. Portsea is approximately 64.6 miles from London, making it a commuter destination for some residents.
Across Hampshire and around Portsea: fuel drain cover
Portsea rests in the PO postcode area, and the teams that answer petrol in diesel call-outs there work the locations near it as well — Portsmouth, Somers Town and Old Portsmouth among them. You need not bring your vehicle to us. Forecourts, supermarket car parks, lay-bys and your own driveway are all places where we work.
Portsea: still at the pump?
No position is better: that is where you now are. Keep it switched off, then ring.