Braichmelyn: Petrol in a Diesel Car? How Worried to Be
Unstarted? Then less anxious than you probably are. Everyone in Braichmelyn begins with "have I ruined it?", and the fair answer is normally no: petrol left in that tank of any diesel stays harmless till priming, cranking or driving draws it into your fuel system. Keep it that way: leave your engine off then phone Petrol in Diesel. The rest of this page explains what petrol really does to a diesel, how to judge how far it has got, and how to make sure it doesn't happen to you a second time.
The engine and petrol in a diesel: what happens
Two tasks fall to diesel on its route through a motor. Before it ignites, it protects — then it combusts. The high-pressure pump and the fuel injectors are made to very fine gaps, and the diesel passing through them is what keeps those surfaces from wearing against one another.
Of those two jobs, petrol handles the first poorly and the second not at all. Being less viscous than diesel, petrol strips away the lubrication a fuel system needs, so a pump running on that mixture wearing itself. It is also made to resist igniting under compression — the opposite of what a diesel needs — which is why you get the knocking.
The shape of the problem is plain when you put those together. Contact doesn't do the harm — circulation does. Petrol in a tank is a fuel fault. The beginning of a mechanical problem is a pump that has been working on that petrol — and whatever a worn pump sheds travels on with the fuel to the fuel injectors downstream.
How bad is petrol in a diesel? Four situations our engineers see in Braichmelyn
Fuelled but not once started — as good as it gets. On a forecourt, and truly only there, that petrol is still limited to that tank — because anywhere else your car was driven to get to it. The task is draining and flushing on the spot.
Started for a second, or just your ignition on. The system has been bled, so petrol has left your tank and got to the fuel filter and the fuel lines. Still generally straightforward: drain, flush, and the filter dealt with.
Driven a few miles. Now the pump has spent these miles running on thinned fuel. Tank, lines, filter, then fresh fuel put through the entire circuit: that's the work, and the way the car was driven counts as much as the distance. Short trips, such as the school run to the local primary school, are one thing. Very different again: a trip to Bangor, under 5 miles away, or some mileage on the Moreton Spur, under 50 miles from Braichmelyn, where the engine never stopped working hard.
Driven on till it protested — clattering, smoke, a ragged idle, a dead throttle. The fuel is not acting like diesel any more, and the engine is telling you. Leave it where it stops: a lay-by, a side street, the verge on Pen y Graig. The drain and flush-through still go first, and they deal with it: when a car is stopped soon, lasting damage is very rare.
Braichmelyn motorists and the petrol in a diesel stories they hear
"Top it up the rest of the way with diesel and it'll be fine" — a myth. It will not. Nothing comes out when you top up — that tank just holds more of the same blend. Percentage isn't how a diesel fuel system tolerates petrol, however much that advice presumes.
If anything, the reverse holds. Myth: "A current diesel can cope with a bit of petrol." A current diesel sends its fuel through more precise components at higher pressure, which makes the protection matter more, not less.
"It starts, it drives, and so there is no harm" — the myth that catches more drivers than any other. Diesel in a petrol motor usually means a motor that won't run: the motorist stops, and so does the harm. Nothing seems to have happened when a diesel fed petrol fires up, ticks over and drives away, as it usually does; meanwhile your pump wears. Being able to run isn't the same as being fine.
An old workaround for a distinct issue is behind this one. Myth: "Add some two-stroke oil and drive the car home." None of what petrol weakened is put back by it — and later, the tank still contains the petrol.
The next start draws petrol back round your pump out of the fuel lines and your filter, where some of that sits once the engine has run. That's why draining your tank yourself doesn't leave you sorted — a myth. And, a can of petrol drained at the kerbside is truly dangerous.
Petrol in a diesel: how does it take place?
Carelessness is rarely the cause, and nobody means to do it. A diesel nozzle generally won't fit a petrol car, yet the smaller petrol nozzle goes into the filler of a diesel almost without resistance — so forecourts make this one mistake easy, and just in that direction.
It happens when habit and your car stop matching. Courtesy car, hire car, or a vehicle that's brand new. Two cars on one driveway, one petrol, one diesel. A forecourt you know, only with its pumps laid out differently. Rushing for a train at Bangor (Gwynedd) and filling up en route. The first fill-up in a diesel Renault Megane after years of driving petrol is precisely the moment it happens. With rain, a call arriving, or children to deal with, the hand just does what it has always done.
How to avoid petrol in a diesel on your next fill-up in Braichmelyn
- Not every forecourt in the UK follows green for unleaded and black for diesel, even if most generally do. Read the pump's label; the colour is only a hint.
- Check your filler flap. Many motors state the fuel inside the flap or on the cap. Look at it on the first fill in a motor you don't know.
- A coloured fob or a sticker on the diesel's key achieves more than any amount of meaning to remember, for a household with one of each.
- "Diesel", aloud, before you pick up the nozzle — each time a new or hired car gets its first tank. It seems daft. It works.
- While 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 block 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.
- Less petrol makes a weaker mixture, so stop the moment you realise — while remembering that the next step is unchanged. It is still not to crank it.
Put petrol in a diesel in Braichmelyn already?
In that case, there is only a short order of things. Starting it is out, and so is switching on the ignition. If you are still at the forecourt — EG Garages or anywhere else — ask the attendants to help you push the car clear of the pump. Next, 0333 366 0103. We'll ask what was put in, about how much, and if it's been run.
If it was AdBlue rather than petrol, say so. That is a separate problem — corrosion and deposits instead of lost lubrication — and it has its own page for Braichmelyn.
Braichmelyn petrol in a diesel jobs: why one costs more than another
Four different tasks sit behind the four scenarios above — which is why there is no fair single quote. What moves your cost is chiefly which of them you are in. Two things follow that: the petrol that went in as a proportion of what your tank holds, then the spot your car is in and whether our van can reach it safely.
What got in, how much, and whether it's run — three questions our engineers ask before pricing, not after, for precisely that reason. The answers turn a range into a straight figure.
About Braichmelyn
Braichmelyn is a suburban area situated on the riverside in Gwynedd, with a mix of semi-detached housing and a population of around 1581 residents. Braichmelyn sits at an elevation of 165 metres, close to the nearby cities and towns of Bangor, Pant, Gerlan, and Gwernydd. Braichmelyn is located near the Menai Strait, with the Snowdonia National Park to the south. Braichmelyn remains a residential community on the outskirts of Bangor, approximately 4.8 miles from the city centre.
Fuel drain cover across Gwynedd, Braichmelyn included
Our vans answering petrol in diesel calls in Braichmelyn, in the LL postcode area, also work the places around it, Pant, Gerlan and Gwernydd among them. You need not move your vehicle to us. Forecourts, supermarket car parks, lay-bys and your own drive are all spots we drain.
Braichmelyn: still at the pump?
The best position there is, then — that's where you are. Turned off it remains; then phone.