Lasswade: Petrol in a Diesel Car? How Worried to Be
Unstarted? Then less worried than you likely are. Until the ignition primes the pump, your starter turns, or your car is driven, petrol in a diesel tank simply sits there and does no harm. Which makes the truthful reply to the first Lasswade query — "have I ruined it?" — usually no. Petrol in Diesel is who to phone, with the engine left off, and so it remains that way. Further down, you will find what petrol actually does inside a diesel, how far it might have got, and how to stop it happening to you a second time.
Your engine and petrol in a diesel: what happens
Two jobs fall to diesel on its journey round a motor. Before it burns, it protects — then it burns. What keeps the surfaces inside the high-pressure fuel pump and your injectors from wearing against each other is the diesel passing through them — they are designed to very fine tolerances.
Of those two jobs, petrol handles the first badly and the second never. The knocking comes from petrol being designed not to ignite when compressed, which is exactly the opposite of what a diesel needs. On top of that it is thinner than diesel, it strips out the protection your system rests on, and any pump working on that mix is wearing itself.
Seen together, they show the shape the issue has. It is movement that does the harm, not contact. Where the petrol is only inside that tank, it's a problem of fuel, nothing more. The beginning of a mechanical problem is a pump that has been labouring on that petrol — and whatever a worn pump sheds moves on with your fuel to the injectors downstream.
Lasswade, petrol in a diesel: four cases, from mild to significant
Fuelled, and never started: no case is better. On a forecourt, and genuinely only there, that petrol is still limited to that tank — because anywhere else the vehicle was driven to get to it. The task is draining and cleaning on the spot.
A moment's running, or just the ignition on. With your system primed, your lines and filter now contain petrol that has come from the tank. Normally nothing more than emptying, flushing and sorting the fuel filter, so still simple.
Driven a few miles. Now the pump has spent those miles working on weakened fuel. The work is that tank, the fuel lines, the fuel filter and fresh fuel through the whole system, and how hard your car was driven counts as much as how far. Short trips, like the school run to the local primary school, are one thing. Very different again: a run to Edinburgh, under 10 miles away, or any miles on the M8, under 10 miles from Lasswade, where the motor never stopped running hard.
It complained, and only then stopped: smoke, clattering, a throttle gone soft, an idle gone lumpy. What you are hearing is the engine reporting fuel that no longer acts like diesel. Whether it's the verge on Eldindean Road, a lay-by or a side road, stop where you are and leave it. The drain and flush-through still go first, and they deal with it: if a car is stopped early, permanent damage is very unusual.
Myths Lasswade drivers hear about petrol in a diesel
It will not be fine. The myth: "Fill it the rest of the way with diesel and it'll be." Topping up takes out nothing; it gives you a bigger tank of the same mix. The idea behind the guidance — that diesel fuel systems tolerate petrol by percentage — is wrong.
Myth: a current diesel copes with a bit of petrol. If anything, the opposite. Smaller components and higher pressure are the way a modern diesel runs its fuel, and that makes the lubrication count more, not less.
One myth that catches drivers off guard: if it starts and drives, it must be unharmed. Diesel in a petrol motor normally means a motor that won't run: the driver stops, and so does the harm. Feed petrol to a diesel and it normally starts, idles and drives away as if nothing has happened — all while its pump wears. Being able to run is not proof of being fine.
Myth: "Add some two-stroke oil and drive it home." It's an outdated fix for a distinct fault. That petrol is still inside the tank after that, and whatever it has diluted is not put back.
The next start sends petrol back round your pump from your lines and the fuel filter, where some of it sits once the engine has been run. That is why draining the tank yourself does not leave you sorted — a myth. Clearing petrol into a can by the roadside is also really dangerous.
Petrol in a diesel: how does it happen?
Nobody does it on purpose, and it's seldom carelessness. The petrol nozzle is the smaller of the two and slides into a diesel filler with almost no resistance; a diesel nozzle mostly will not go into a petrol car at all. The forecourt makes it easy, and the error runs one way.
The moment routine stops matching the vehicle is the moment it occurs. A car that's new to you — a hire car, on loan as a courtesy car, or brand new. One petrol and one diesel on the driveway of the same household. The pumps in a different order on a familiar forecourt. A hurried fill on the way to Eskbank with a train to catch. Years of petrol vehicles behind you, a diesel Volkswagen Passat in front of you at the forecourt for its first tank — that's when. The hand repeats what it has always done when you add rain, a phone call or a back seat full of kids.
Lasswade people: how to prevent petrol in a diesel next time
- Not every forecourt in the UK follows green for unleaded and black for diesel, even if most generally do. Read the petrol pump's label; the colour is only a clue.
- The first fill in an unfamiliar motor is the time to check your filler flap — on it, or on the cap, plenty of cars state the fuel to use.
- One of each in the home? Label the key to the diesel — a bright fob, a sticker — because intending to remember isn't enough.
- Before the nozzle comes off the petrol pump the first time you fill a hired or new car, say "diesel" out loud. Silly, perhaps, yet it does the trick.
- While you're thinking about something else, this is an easy mistake to make — so put your phone away.
- Some diesels have a filler designed to block a petrol nozzle, and devices you can add exist for motors without one. Such an inhibitor helps up to a point — as a backstop, not a reason to stop reading the petrol pump.
- Less petrol means a thinner mixture, so stop as soon as you notice — while remembering that your next stage is unchanged. It's still not to start it.
Petrol already in a diesel around Lasswade? Begin here
Short and simple, then, is the order of things. Leave it unstarted, with the ignition switched off too. Ask the attendants to help you push it away from the petrol pump if you are still on the forecourt, whether that's Tesco or somewhere else. Then phone 0333 366 0103 and tell us what got in, about how much, and if it's run.
Corrosion and deposits form the problem with AdBlue, where petrol brings lost protection. So if it was AdBlue, say so — and read its own Lasswade page.
One petrol in a diesel job in Lasswade costs more than another. Why?
The four situations above are four separate tasks, so no single quote for this would be fair. Which of them you're in is mostly what moves your cost. Beyond that it is the proportion — how much petrol went in against how much your tank holds — and after that where the vehicle is and whether a technician can reach it safely.
Ahead of any quote, not after, we ask three queries: the fuel that was put in, the volume, and whether it has run. That is why. A range becomes a straight figure once the answers are in.
About Lasswade itself
Lasswade is a suburban area situated on the River North Esk in Midlothian, with a mix of semi-detached housing and local amenities. Lasswade sits at an elevation of 93 metres, approximately 6 miles southeast of Edinburgh's city centre. Lasswade is close to nearby places such as Eldindean, Waverley, and Quarryhead, and is part of the wider Edinburgh urban area. Lasswade has a population of around 5233 people, with a range of local services and facilities.
Across Midlothian and around Lasswade: fuel drain cover
Lasswade rests in the EH postcode area, and the vans that answer petrol in diesel call-outs there work the locations near it as well — Eldindean, Waverley and Quarryhead among them. We drain wherever the vehicle is — your own driveway, a lay-by, a supermarket car park, a forecourt — so it does not have to come to us.
In Lasswade and still at the petrol pump?
The best position there is, then — that's where you are. Keep it off. Phone.