Should You Worry? Petrol in a Diesel Car in Durns Town
Unstarted? Then less anxious than you probably feel. Until the ignition primes the pump, your starter cranks, or your vehicle is driven, petrol in a diesel tank simply waits there and does no harm. Which makes the truthful reply to the first Durns Town query — "have I ruined it?" — usually no. To leave it like that, phone Petrol in Diesel and leave the engine switched off. Further down, you will find what petrol really does inside a diesel, how far it may have gone, and how to stop it happening to you a second time.
What petrol in a diesel does to your engine
Two jobs fall to diesel on its journey round a motor. Oiling comes before burning; it does both. What keeps the surfaces inside your high-pressure pump and the injectors from wearing against one another is your diesel flowing through them — they are designed to extremely fine clearances.
The second job petrol does not do at all, and the first it does poorly. A pump working on a petrol mixture is wearing itself out, because petrol is thinner than diesel and takes away the lubrication your fuel system depends on. Petrol is also made to resist igniting under compression — the reverse of what a diesel wants from its fuel — and that is where any clattering comes.
Put those together and the shape of the issue is clear. Contact does not do the harm — 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 your injectors downstream, which is why a pump that has worked on that petrol is where a mechanical fault starts.
Four scenarios our engineers see in Durns Town: how bad is petrol in a diesel?
Filled up, never started. The best case there can be. At a forecourt, and really only there, that petrol is still limited to your tank — since everywhere else the vehicle was driven to reach it. The task is emptying and flushing on the spot.
The ignition switched on, or a short start. The fuel system has been primed, so petrol has left that tank and got to the filter and the fuel lines. That's normally still a straightforward job — a drain, a flush, and the filter seen to.
Those few miles on the road were the pump working on fuel weakened by petrol the whole way. Tank, lines, filter, then clean fuel run through the whole system: that's this work, and the way your car was driven matters as much as the mileage. The school run to St Luke's Church of England Primary School is one thing. Getting as far as Southampton, under 15 miles away, makes a very different job — as does any distance on the M27, under 10 miles from Durns Town, with the engine running hard all the way.
It protested, and only then stopped: smoke, knocking, a throttle gone soft, an idle gone lumpy. That is your motor telling you its fuel no longer is behaving like diesel. Stop on the spot — on the verge on St James Road, at the kerb, down a side road — and do not move it. What goes first is still the fuel drain and flush-through, and that sorts it out, with lasting damage very unusual if a vehicle is pulled over quickly.
Stories Durns Town 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. Topping up takes out nothing; it gives you a bigger tank of the same mixture. The idea behind that advice — that diesel fuel systems accept petrol by percentage — is wrong.
"Modern diesels can handle a little petrol" — a myth, and closer to the reverse. At higher pressure, through smaller components: that is how a current diesel handles its fuel, and so the lubrication counts more, not less.
The myth that catches people out: if it starts and drives, it must be unharmed. Feed diesel to a petrol engine and it usually won't run, so the motorist 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 will; meanwhile the pump grinds. Being able to run is not proof of being fine.
Myth: "Add some two-stroke oil and drive it home." It is an old fix for a distinct fault. What petrol has thinned remains thinned, and that petrol remains inside that tank regardless.
Myth: "Drain the tank yourself and you're sorted." Once your engine has been run, some of that petrol is no longer inside the tank: it is in the fuel filter and the lines, and it goes straight back through the pump at your next start. It's also really dangerous to drain petrol into a can by the roadside.
Why petrol in a diesel happens at all
A careless moment is seldom the cause, and no one means to do it. One way only, because of the nozzles: the smaller petrol one slides inside a diesel filler with almost no resistance, whereas the diesel one generally won't fit a petrol car. That is how the forecourt makes it easy.
When habit and the car stop matching, it occurs. Courtesy car, hire car, or a motor that is new. Households running one of each, petrol and diesel. A forecourt you know, but with its pumps arranged differently. Fuelling up in a hurry en route to Sway, with a train to catch. A new-to-you diesel Volkswagen Golf, its first fuelling, and a motorist accustomed to petrol: precisely when it happens. With rain, a call coming in, or a car full of children to deal with, the hand simply does what it always has.
Durns Town drivers: how to avoid petrol in a diesel next time
- A green handle for unleaded and black for diesel is normal in the UK — but not on every forecourt. Trust the label on the petrol pump, not the colour.
- The first fill in an unfamiliar motor is the time to check your filler flap — on it, or on the cap, many cars state the fuel they take.
- A coloured fob or a sticker on the diesel's key does more than any amount of intending to remember, in a house with one of each.
- 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 sounds daft and it works.
- Thinking about something else is when this becomes an easy mistake to make, so tuck your phone away and keep your mind on the pump.
- Add-on devices are available for motors without one, and some diesels come with a filler that won't accept a petrol nozzle. Useful — but a backstop at best, never a reason to stop checking the label.
- Stop the moment you realise. Less petrol inside that tank makes a thinner blend. It does not change what to do next, which is still not to start the car.
Durns Town: already put petrol in a diesel?
Short and simple, then, is the order of things. Leave it unstarted, with your ignition switched off as well. The attendants at the forecourt — whether at Shell itself or wherever you filled up — will usually help roll it clear of the petrol pump if you ask. What got in, about how much, and if it has run: tell us that when you call 0333 366 0103.
Say so if it was AdBlue instead of petrol: it's a different issue, with its own page for Durns Town, since AdBlue brings corrosion and deposits rather than lost protection.
What makes one Durns Town petrol in a diesel task cost more than the next
The four scenarios above are four different jobs, so no single price for this would be fair. What moves your cost is mostly which of them you're in. After that it is the share — how much petrol was put in against how much the tank takes — and after that where your car is and whether a technician can reach it safely.
That is why our technicians ask three queries before costing instead of after: what went in, how much, and whether it has run. With those replies, you get a straight figure instead of a range.
About Durns Town and where it is
Durns Town is a suburban area in Hampshire, situated inland at an elevation of approximately 40 metres. Durns Town lies near the cities of Southampton and Bournemouth, and is surrounded by nearby places such as Birchy Hill and Sway. Durns Town has a population of around 1823 people, predominantly living in detached housing. Durns Town is located about 80 miles from London, making it a commuter hub for those working in the capital.
Durns Town and Hampshire: where our fuel drain cover reaches
Our vans answering petrol in diesel call-outs around Durns Town, in the SO postcode area, equally work the spots around it, Birchy Hill, Sway and Mount Pleasant included. You need not bring your vehicle to us. Forecourts, supermarket car parks, lay-bys and your own drive are all spots we drain.
Durns Town: still at the petrol pump?
The best position there is, then — that's where you are. Keep the vehicle switched off, and ring.