How Worried Should You Be? Petrol in a Diesel Car in Fall Ings
Unstarted? Then less worried than you probably are. Everyone around Fall Ings begins with "have I wrecked it?", and the fair answer is generally no: petrol resting in your tank of a diesel remains harmless until priming, cranking or driving draws it into the fuel system. Leave your engine off and call Petrol in Diesel — that is how you keep it like that. The rest of this page covers what petrol really does to a diesel, how to tell how far it has got, and how to make sure it doesn't happen to you a second time.
Petrol in a diesel: what does it do to the engine?
Diesel does two jobs on its way through a motor. Lubricating comes before burning; it does both. The high-pressure fuel pump and the fuel injectors are built to extremely fine gaps, and your diesel passing through them is what keeps those surfaces from wearing down against one another.
Poorly at the first, not at all at the second: that's petrol. Being less viscous than diesel, petrol strips out the lubrication 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 why you hear the knocking.
Combined, those leave the shape of the issue clear. Not contact but movement is what causes the damage. All a tank with petrol in it amounts to is a fuel issue. A pump that has been working on that petrol is the beginning of a mechanical one, and whatever a worn pump sheds travels on with your fuel to your injectors downstream.
How serious is petrol in a diesel? Four scenarios our technicians see around Fall Ings
The best case there is: filled up, not once started. That petrol is in that tank and just your tank, and the job is a drain and a flush where the car sits. This is the one situation that can only really take place on a forecourt, since anywhere else your car has been driven to get there.
A moment's running, or just your ignition on. The fuel system has been primed, and so petrol has left that tank and reached the filter and your lines. Still normally easy: drain, flush, and the fuel filter seen to.
Your pump has worked a few miles on weakened fuel — that's what driving it meant. Miles is only half of it; how hard it was driven counts just as much. Either way the work includes your tank, the fuel lines, the filter and fresh fuel through the entire system. On the school run to Wakefield St Marys Church of England Voluntary Aided Primary School, the miles is short. Getting as far as Wakefield, under a mile away, makes a very different task — as does any miles on the M1, under 3 miles from Fall Ings, with the motor working hard all the way.
It complained, and only then stopped: smoke, clattering, a throttle gone soft, an idle gone lumpy. The fuel isn't acting like diesel any more, and your motor is saying so. Whether it is the verge on Doncaster Road, a lay-by or a side street, stop where you are and leave it. What goes first is still the drain and flush, and that takes care of it, with long-term damage very uncommon if a car is pulled over early.
What Fall Ings people get told about petrol in a diesel — and the myths in it
It will not be fine. The myth: "Fill it the rest of the way with diesel and it'll be." Nothing is removed by topping up — you are left with a fuller tank, still the same mixture. Percentage is not how a diesel fuel system tolerates petrol, however much that guidance assumes.
"Newer diesels can handle a little petrol" — a myth, and closer to the opposite. Finer parts and higher pressure are the way a newer diesel runs its fuel, and that makes the lubrication count more, not less.
This is the one that fools people. Myth: "If it starts and drives, there's no harm done." The motorist of a petrol engine fed diesel usually stops, since it will not run, and the harm stops with them. A diesel fed petrol generally starts, idles and drives away as if nothing has happened, while the pump wears. Running does not mean fine.
Myth: "Add some two-stroke oil and drive it home." It is an outdated fix for a separate issue. It does not put back what petrol has thinned, and the petrol is still inside the tank after that.
Once the engine has run, part of the petrol sits in your filter and the lines, not that tank — and the next start sends it right back through the pump. So the myth "drain your tank yourself and you're sorted" doesn't hold. On top of that, petrol cleared into a can by the road is genuinely hazardous.
Petrol in a diesel: how does it happen?
Carelessness is seldom the cause, and nobody means to do it. A diesel nozzle mostly won't fit a petrol motor, but the smaller petrol nozzle goes into the filler of a diesel almost without resistance — so forecourts make this one error easy, and just in one direction.
When habit and the vehicle stop matching, it takes place. Hire cars, courtesy cars, and motors that are new to you. Two vehicles on one drive, one petrol, one diesel. A forecourt you know, but with its pumps arranged differently. A rushed fill en route to Wakefield Kirkgate with a train to catch. The first fill-up in a diesel Renault Megane after years of driving petrol is exactly the moment it takes place. Add rain, a phone call or a back seat full of children, and your hand repeats what it has always done.
How to prevent petrol in a diesel on your next fill-up in Fall Ings
- Check the pump, not the colour. In the UK unleaded handles are normally green and diesel black, yet not on every forecourt. The label is what matters.
- The first fill in a new vehicle is the time to check your filler flap — inside it, or on the cap, plenty of cars state the fuel they take.
- Mark the key. In a home with one of each, a coloured fob or a sticker on the diesel's key does more than any amount of meaning to remember.
- "Diesel", aloud, before you lift the nozzle — each time a new or hired car gets its first tank. It sounds silly. It does the trick.
- Thinking about something else is when this becomes an easy mistake to make, and so put your phone away and keep your mind on the pump.
- A misfuel inhibitor helps, up to a point. Some diesels have a filler built to refuse a petrol nozzle, and add-on devices exist for vehicles without one. They are a backstop, not a reason to stop checking the petrol pump.
- As soon as you notice, stop: less petrol in your tank means a thinner mixture. What to do next does not change, though — still don't fire it up.
Petrol already in a diesel in Fall Ings? Start here
Then, there's only a short order of things. Never start it, and do not switch the ignition on. If you're still at the forecourt — BP or anywhere else — ask the attendants to help you push the vehicle clear of the petrol pump. What went in, about how much, and whether it has run: tell us those when you call 0333 366 0103.
If it was AdBlue rather than petrol, say so. That is a separate problem — corrosion and deposits rather than lost lubrication — and it has its own page for Fall Ings.
Fall Ings petrol in a diesel tasks: why one costs more than another
The four scenarios above are four separate jobs, so no single price for this would be honest. What shifts your cost is chiefly which of them you are in. Where the car is counts too, and whether a van can safely reach it, after the ratio of petrol to what your tank holds.
Before any quote, not after, come three queries: the fuel that went in, the quantity, and whether it's run. That is why. Given the replies, there is a straight figure instead of a range.
About Fall Ings itself
Fall Ings is a suburban area located on the riverside in West Yorkshire, with a mix of flat housing and local amenities. Fall Ings sits near the city of Wakefield, at an elevation of 27 metres, and is close to nearby places such as Calder Vale and Belle Vue. Fall Ings is part of the larger Wakefield urban area, with easy access to the city centre. Fall Ings has a population of approximately 2525 people, living in a predominantly flat-based residential community.
Fuel drain cover in Fall Ings and across West Yorkshire
Petrol in diesel call-outs in Fall Ings — part of the WF postcode area — go to vans that likewise cover the locations round it, Calder Vale, Belle Vue and Belle Isle among them. Our technicians drain wherever the vehicle is — your own driveway, a lay-by, a supermarket car park, a forecourt — so it never needs to come to us.
Still at the petrol pump around Fall Ings?
Then you are in the best position there is. Keep it turned off, then ring.