How Worried Should You Be? Petrol in a Diesel Car in Shenfield
Provided it has not been started, you can worry less than you likely are. Everyone around Shenfield begins with "have I ruined it?", and the fair answer is usually no: petrol left inside your tank of a diesel remains harmless till priming, cranking or driving draws it into the fuel system. Keep it that way: leave your engine off then call Petrol in Diesel. Keep reading for three things: the effect petrol has inside a diesel motor, the signs of how far it has spread, and ways to make sure you never repeat it.
What petrol in a diesel does to the motor
Passing through a motor, diesel is doing two jobs at the same time. It ignites, and before it burns it protects. Designed to very fine tolerances, your injectors and the pump rely on the diesel flowing through them to keep their surfaces from wearing against one another.
Petrol handles the first job badly and the second not at all. A pump running on a petrol blend is wearing itself out, because petrol is thinner than diesel and takes away the lubrication the fuel system depends on. Petrol is also designed to resist igniting under compression — the opposite of what a diesel wants from its fuel — and that is where any knocking starts.
Put those together and the shape of the problem is plain. Contact doesn't do the damage — circulation does. All a tank with petrol in it amounts to is a fuel issue. Whatever a worn pump sheds travels on, borne by the fuel, into the injectors downstream, which is why a pump that has worked on the petrol is where a mechanical fault starts.
How serious is petrol in a diesel? Four scenarios our engineers see around Shenfield
Fuelled up, not once started. The best case there can be. That petrol is in that tank and just your tank, and the task is a drain and a flush where the car sits. This is the one scenario that can only truly take place at a forecourt, because anywhere else the vehicle has been driven to get there.
Ignition on, or started for a moment. With your system primed, your lines and filter already hold petrol that came from the tank. Still generally straightforward: drain, flush, and the filter dealt with.
Driven a couple of miles. Now the pump has spent these miles working on weakened fuel. Mileage is only half of it; how hard it was driven counts just as much. Either way the work runs to the tank, the lines, your filter and fresh fuel through the entire circuit. Driving the kids to Shenfield St. Mary's Church of England Primary School is one sort of trip. Any distance on the M25, under 5 miles from Shenfield, means the motor has worked hard throughout, and a run to Chelmsford, under 10 miles away, makes a very different task as well.
Driven on till it complained — knocking, smoke, a ragged idle, a soft throttle. That is your motor telling you its fuel no longer is acting like diesel. Stop wherever you are — the verge on Friar's Avenue, a lay-by, a side street — then leave the car there. Lasting damage is very unusual if a vehicle is stopped early, and the fuel drain and flush-through that still go first deal with it.
What Shenfield people 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. Nothing is removed by topping up — you are left with a bigger tank, still the same mix. A diesel fuel system doesn't tolerate petrol by percentage in the way that advice supposes.
Myth: "A current diesel can cope with a bit of petrol." If anything, the opposite. At higher pressure, through finer components: that is how a current diesel moves its fuel, so the lubrication counts for more, not less.
This is the one that catches people. Myth: "If it starts and drives, there's no harm done." A petrol engine fed diesel generally will not run, so the driver stops and the damage stops with them. Nothing seems to have happened when a diesel fed petrol fires up, ticks over and drives away, which it usually does; meanwhile the pump grinds. Being able to run is not proof of being fine.
Myth: "Add some two-stroke oil and drive the car home." It is an outdated workaround for a different fault. That petrol is still in that tank after that, and whatever it has thinned is not put back.
The next start sends petrol back round your pump from the lines and your filter, where some of that sits after your engine has been run. That is why draining the tank yourself does not sort it — a myth. And, a can of petrol drained at the roadside is truly dangerous.
How it happens: petrol in a diesel
A careless moment is rarely the cause, and nobody means to do it. The forecourt makes it easy: the petrol nozzle is the smaller of the two, and it slides into a diesel filler with almost no resistance, while a diesel nozzle mostly won't go into a petrol motor at all. So the mistake runs one way.
Habit and your car getting out of step is how it happens. Courtesy car, hire car, or a motor that's brand new. One petrol and one diesel on the driveway of the same household. A well-known forecourt with the pumps in a different order. A hurried fill on the way to the nearest station with a train to catch. A new-to-you diesel Volkswagen Passat, its first fuelling, and a driver used to petrol: precisely when it takes place. Throw in a back seat full of children, a phone call or rain, and the hand takes over.
Preventing petrol in a diesel next time you fill up around Shenfield
- Check the petrol pump, not the colour. In the UK unleaded handles are generally green and diesel black, yet not on each forecourt. The label is what matters.
- In a car you don't know, look inside the flap over the filler or at the cap before your first fill: plenty of motors print the fuel type there.
- Good intentions count for less than a sticker or a fob in a bright colour on your diesel's key when a household has one of each. So mark 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 pump. It seems daft and it does the trick.
- Whilst you are thinking about something else, this is an easy mistake to make — so put the phone away.
- A misfuel inhibitor helps, up to a point. Some diesels have a filler designed to refuse a petrol nozzle, and add-on devices exist for cars without one. They are a safety net, not a reason to stop checking the pump.
- Less petrol makes a thinner blend, and so stop the moment you realise — while remembering that the next stage is unchanged. It is still not to fire it up.
Already put petrol in a diesel in Shenfield?
Then, there is just a short order of things. Starting it is out, and so is switching on your ignition. Ask the staff to help you push it clear of the pump if you are still on the forecourt, whether that is BP or somewhere else. Phone 0333 366 0103 next, with three answers — the fuel, the rough quantity, and whether it's run.
If it was AdBlue rather than petrol, say so. That is a separate fault — corrosion and deposits and not lost lubrication — and it has its own page for Shenfield.
Shenfield petrol in a diesel tasks: why one costs more than another
Four separate tasks lie behind the four situations above — which is why there's no honest single price. The situation itself does most of the work of moving the cost. Where the car is matters too, and whether our van can safely get to it, after the proportion of petrol to what the tank takes.
Before any quote, not after, come three queries: the fuel that was put in, its quantity, and whether it's run. That's why. Those answers are what change a range into one firm number.
About Shenfield, for a moment
Shenfield is a suburban area in Essex, situated approximately 21 miles east of London and 10 miles northwest of Chelmsford. Shenfield sits at an elevation of around 80 metres, in a gently undulating landscape of inland Essex. Shenfield has a mix of housing types, but is predominantly characterised by detached homes, and is close to nearby places such as Hutton, Hutton Mount, and Brentwood.
Across Essex and in Shenfield: fuel drain cover
Hutton, Hutton Mount and Brentwood are among the places around Shenfield that the same teams work, answering petrol in diesel calls across Shenfield's CM postcode area. You need not bring the car to us. Forecourts, supermarket car parks, lay-bys and your own drive are all places we drain.
Still at the pump around Shenfield?
No position is better: that is where you now are. Ring, and leave it switched off.