How Worried Should You Be? Petrol in a Diesel Car in Brittens
Far less than you probably are, provided it hasn't been started. Petrol sitting in a diesel tank does nothing to the motor until something draws it through your fuel system — the ignition priming the pump, your starter, or the drive on its own. So the fair answer to the first question everyone around Brittens asks, "have I ruined it?", is usually no. To keep it that way, phone Petrol in Diesel then leave your engine switched off. Further down, this page sets out what petrol actually does inside a diesel, how far it might have got, and how to stop it happening to you again.
What petrol in a diesel does to your engine
On its way through a motor, diesel does two tasks. Oiling comes before burning; it does both. Made to very fine tolerances, your injectors and the pump depend on your diesel moving through them to stop their surfaces wearing against one another.
The second task petrol does not do at all, and the first it does badly. A pump working on a petrol mix is wearing itself out, since petrol is thinner than diesel and takes away the protection the fuel system depends on. Petrol is also made to resist igniting under compression — the opposite of what a diesel needs from its fuel — and that's where the rattling starts.
Taken together, they show the shape the trouble takes. Contact does not do the harm — circulation does. Where that petrol is only in your tank, it's a fault of fuel, nothing more. The beginning of a mechanical problem is a pump that has been running on that petrol — and whatever a worn pump sheds moves on with your fuel to the fuel injectors downstream.
Brittens, petrol in a diesel: four cases, from mild to major
Filled but not once started — the best it gets. That petrol is inside your tank and only the tank, and the task is a drain and a flush where the vehicle stands. This is the one situation that can only truly take place at a forecourt, because anywhere else the car has been driven to get there.
A brief spell of running, or merely your ignition on. Once primed, the system has drawn petrol out of the tank as far as your filter and the lines. That's generally still a simple task — a drain, a flush, and your filter dealt with.
Your pump now spent a couple of miles on thinned fuel — that is what driving the car meant. How hard the car was driven counts as much as how far, and this work covers your tank, the fuel lines, the fuel filter and clean fuel through the whole circuit. Driving the kids to Paulton Infant School is one kind of trip. Very different once more: a trip to Bath, under 10 miles away, or any mileage on the M32, under 15 miles from Brittens, where the motor never stopped labouring hard.
Driven on until it complained — clattering, smoke, a ragged idle, a dead throttle. That's your motor telling you its fuel has stopped acting like diesel. Pull up on the spot — on the verge on Brookside Close, at the kerb, down a side road — and don't move it again. What goes first is still the drain and flush, and that takes care of it, with permanent damage very uncommon if a car is pulled over quickly.
What Brittens motorists get told about petrol in a diesel — and the myths in it
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. That guidance supposes a diesel fuel system handles petrol by percentage. It doesn't.
"Modern diesels can handle a little petrol" — a myth, and nearer the reverse. Lubrication matters more on newer diesels, not less, since their fuel runs through smaller parts at higher pressure.
The myth that catches motorists out: if it starts and drives, it must be unharmed. The motorist of a petrol engine fed diesel normally stops, since it will not run, and the harm stops with them. Nothing seems to have happened when a diesel fed petrol fires up, ticks over and drives away, which it usually will; meanwhile your pump grinds. Fine and running are not the same at all.
An outdated fix for a distinct fault lies behind this one. Myth: "Add some two-stroke oil and drive the car home." None of what petrol weakened gets put back by it — and afterwards, the tank still holds that petrol.
The next start draws petrol back round your pump from the lines and the fuel filter, where some of it sits after the motor has been run. That's why a DIY tank drain doesn't sort it — a myth. Clearing petrol into a can by the roadside is also genuinely risky.
Why petrol in a diesel occurs so easily
Carelessness is rarely the cause, and nobody means to do it. 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 easy, and the mistake runs one way.
The moment routine stops matching your car is the moment it takes place. Courtesy car, hire car, or a motor that is new. Two motors on one drive, one petrol, one diesel. A forecourt you know, only with its pumps laid out differently. Fuelling up in a rush en route to Oldfield Park, with a train to catch. A new-to-you diesel Volkswagen Golf, its first fuelling, and a driver used to petrol: exactly when it happens. Add rain, a phone call or a back seat full of children, and your hand repeats what it has always done.
Preventing petrol in a diesel next time you fill up around Brittens
- 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.
- Many cars state the fuel type inside the filler flap or on the cap, so check there on your first fill in any car you do not know.
- Good intentions count for less than a sticker or a fob in a bright colour on your diesel's key if a house has one of each. So label it.
- Say it before you lift it. On the first fill in a new or hired car, say "diesel" aloud before you take the nozzle off the petrol pump. It seems silly and it works.
- While you are thinking about something else, this is an easy mistake to make — so tuck your phone away.
- A misfuel inhibitor helps, up to a point. Some diesels have a filler built to refuse a petrol nozzle, and add-on devices are available for motors without one. They are a safety net, not a reason to stop reading the petrol pump.
- Less petrol means a weaker mixture, so stop the moment you realise — while remembering that the next step is unchanged. It is still not to crank it.
Petrol already in a diesel in Brittens? Start here
Then the order of things is short. Leave it unstarted, with the ignition off as well. If you're still on the forecourt — Murco or anywhere else — ask the attendants to help you roll the vehicle clear of the pump. Then ring 0333 366 0103 and tell us what went in, about how much, and whether it has run.
If it was AdBlue instead of petrol, say so. That's a separate fault — corrosion and deposits rather than lost protection — and it has its own page for Brittens.
Brittens petrol in a diesel jobs: why one costs more than another
Four different jobs lie behind the four scenarios above — which is why there is no honest single quote. What moves the cost is mostly which of them you're in. The proportion matters next, meaning how much of the tank is petrol, and then the position of your car and whether reaching it is safe for our van.
Three queries come first, before any quote, instead of after — what was put in, how much, has it run — and that is the reason. Those answers are what turn a range into one firm number.
About Brittens, briefly
Brittens is a locality in Somerset, situated inland at an elevation of 114 metres, approximately 7.9 miles from the city of Bath. Brittens is characterized by its semi-detached housing and is located near other places such as Paulton, Winterfield, and Withy Mills. Brittens has a population of around 2539 residents and is about 103 miles west of London.
Brittens and Somerset: where our fuel drain cover runs
Brittens waits in the BS postcode area, and our teams that answer petrol in diesel jobs there work the locations near it as well — Paulton, Winterfield and Withy Mills among them. A forecourt, a supermarket car park, a lay-by or your own driveway are all places we drain, and the vehicle does not need to move to us.
In Brittens and still at the petrol pump?
Then you are in the best spot there can be. Keep it off. Ring.