Petrol in a Diesel Car in Sough: How Worried Should You Be?
Less than you probably are, if it has not been started. Everyone around Sough starts with "have I wrecked it?", and the fair answer is generally no: petrol left in that tank of a diesel remains harmless until priming, cranking or driving draws it into your fuel system. Leave your motor off and call Petrol in Diesel — that is how you keep it that way. What petrol actually does to a diesel, how to judge how far it has gone, and how to keep it from happening again: that is the remainder of this page.
Your engine and petrol in a diesel: what happens
Passing through a motor, diesel is doing two jobs at the same time. Before it ignites, it lubricates — and then it burns. Your high-pressure pump and the injectors are built to very fine tolerances, and the diesel passing through them is what keeps those surfaces from wearing down against each other.
Of these two tasks, petrol handles the first badly and the second not at all. A pump running on a petrol mix is wearing itself out, because petrol is thinner than diesel and strips out the lubrication your fuel system relies on. Petrol is also made to resist igniting under compression — the reverse of what a diesel wants from its fuel — and that's where the rattling starts.
The shape of the issue is plain when you put those together. Contact does not do the harm — circulation does. All a tank with petrol in it amounts to is a fuel problem. After your pump has been running on that petrol, a mechanical problem has started: whatever is shed by a pump that is wearing down is carried downstream to the injectors with your fuel.
Four scenarios our technicians see around Sough: how bad is petrol in a diesel?
The best case there is: filled up, not once started. Just your tank has petrol in it, so the job is draining the tank and rinsing your system where the car sits. This situation can only really happen on a forecourt: anywhere else, the car got there by being driven.
Ignition on, or started for a moment. Once primed, the fuel system has drawn petrol from that tank up to the fuel filter and your lines. Still generally straightforward: drain, flush, and the filter dealt with.
Your pump now worked a few miles on diluted fuel — that is what driving the vehicle meant. The work is the tank, the fuel lines, your filter and clean fuel through the whole circuit, and how hard the vehicle was driven matters as much as how far. On the school run to Darwen, St Barnabas CofE Primary Academy, the distance is small. Any mileage on the M65, under 3 miles from Sough, means your engine working hard throughout, and a run to Preston, under 15 miles away, makes a very different job too.
Knocking, a lumpy idle, smoke, a throttle gone soft: driven till it complained. That is the motor telling you its fuel has stopped acting like diesel. Leave it wherever it has stopped: a lay-by, a quiet street, the verge on Hampden Avenue. A car stopped early very rarely has long-term damage, as the drain and the flush, which still come first, deal with it.
What Sough drivers get told about petrol in a diesel — and the stories in it
It will not be fine. The myth: "Fill it the rest of the way with diesel and it will be." Nothing is removed when you top up — your tank simply carries more of the same mixture. That guidance assumes a diesel fuel system tolerates petrol by percentage. It doesn't.
Myth: "A modern diesel can cope with a bit of petrol." If anything, the reverse. A modern diesel runs its fuel through finer components at higher pressure, which makes the protection matter more, not less.
The myth that catches drivers off guard: if it starts and drives, it must be unharmed. The motorist of a petrol motor fed diesel normally stops, because it will not run, and the harm stops with them. Nothing looks to have happened when a diesel fed petrol fires up, ticks over and drives away, as it usually will; meanwhile your pump grinds. Being able to run isn't the same as being fine.
Myth: "Add some two-stroke oil and drive the car home." It's an old fix for a different issue. It doesn't put back what petrol has thinned, and the petrol is still inside the tank later.
Once your engine has run, part of that petrol is in your filter and the lines, not your tank — and the next start pulls it right back through the pump. So the myth "drain your tank yourself and you are sorted" doesn't hold. It is also genuinely risky to drain petrol into a can by the kerbside.
How does petrol in a diesel happen?
No one does it on purpose, and it is rarely carelessness. A diesel nozzle generally won't fit a petrol vehicle, yet 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.
The moment habit stops matching the vehicle is the moment it happens. Courtesy car, hire car, or a motor that's brand new. A household with one petrol and one diesel on the drive. A well-known forecourt with the pumps in a different order. Fuelling up in a rush on the way to Darwen, with a train to catch. A new-to-you diesel BMW 3 Series, its first fuelling, and a motorist accustomed to petrol: exactly when it takes place. Add a back seat full of kids, a phone call or rain, and habit takes over.
Next time you fill up around Sough: avoiding petrol in a diesel
- A green handle for unleaded and black for diesel is usual in the UK — but not on every forecourt. Go by the label on the pump, not the colour.
- The first fill in an unfamiliar car is the time to check the filler flap — on it, or on the cap, many vehicles state which fuel they take.
- A coloured fob or a sticker on the diesel's key achieves more than any amount of intending to remember, for a house with one of each.
- Before the nozzle leaves the pump the first time you fuel a hired or new car, say "diesel" out loud. Daft, perhaps, but it works.
- Put the phone away. This is an easy mistake to make whilst you're thinking about something else.
- Up to a point, a misfuel inhibitor helps: some diesels have a filler built to block a petrol nozzle, and add-on devices exist for the rest. Count it as a backstop, then keep reading the petrol pump.
- As soon as you realise, stop: less petrol inside that tank means a weaker mixture. What to do next doesn't change, though — still do not start it.
Petrol already in a diesel around Sough? Start here
Short and simple, then, is the order of things. Do not fire it up, and don't switch your ignition on. If you're still on the forecourt — Shell or anywhere else — ask the staff to help you push it clear of the petrol pump. Then call 0333 366 0103 and tell us what went in, about how much, and whether it has run.
Corrosion and deposits form the issue with AdBlue, whereas petrol brings lost protection. So if it was AdBlue, say so — and see its own Sough page.
Sough 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. Mostly, the cost moves with which situation you are in. The proportion counts next, meaning how much of that tank is petrol, and then the position of the vehicle and whether getting to it is safe for our van.
Before any quote, not after, we ask three questions: your fuel that was put in, its amount, and whether it's run. That is why. Given the answers, there is a straight figure instead of a range.
About Sough
Sough is a suburban area in Lancashire, situated on the riverside with a mix of terraced housing and other residential properties. Sough sits at an elevation of 198 metres, approximately 11 miles from Preston and 179 miles from London. Sough is close to nearby places such as Spring Vale, Whitehall, and Radford, and has a population of around 5817 residents.
Fuel drain cover across Lancashire, Sough included
The vans answering petrol in diesel jobs in Sough, in the BB postcode area, also work the places around it, Spring Vale, Whitehall and Radford included. A forecourt, a supermarket car park, a lay-by or your own drive are all locations we work, and your car does not need to come to us.
In Sough and still at the petrol pump?
In that case, you couldn't be in a better position. Phone, and keep it turned off.