Should You Worry? Petrol in a Diesel Car in Oakdale
Probably less than you are now — provided nobody has started the vehicle. "Have I wrecked it?" is the first question everyone around Oakdale asks, and the honest answer is normally no, because petrol resting in a diesel tank harms nothing till it's drawn through the fuel system — by ignition priming, by the starter, or by driving. Leave your motor off and phone Petrol in Diesel — that keeps it that way. Further down, this page sets out what petrol actually does inside a diesel, how far it might have got, and how to stop it happening to you a second time.
What petrol in a diesel does to your engine
On its way through a motor, diesel does two jobs. Before it burns, it lubricates — then it burns. Very fine clearances are built into the injectors and your high-pressure pump, and just the diesel flowing through stops those surfaces grinding together.
Petrol handles the first task badly and the second not at all. The knocking comes from petrol being made not to ignite when compressed, which is exactly the reverse of what a diesel needs. On top of that it is runnier than diesel, it strips out the lubrication the system rests on, and any pump working on such a blend is wearing itself.
Put those together and the shape of the issue is clear. Not contact but circulation is what causes the harm. Any tank with petrol in it is a fuel fault. A pump that has been working on that petrol is the start of a mechanical one, and whatever a worn pump sheds moves on with the fuel to your injectors further on.
Four scenarios our technicians see around Oakdale: how serious is petrol in a diesel?
Fuelled but not once started — as good as it gets. That petrol is inside your tank and just that tank, and the job is a drain and a flush where your car stands. This is the one scenario that can only really take place on a forecourt, because anywhere else your car has been driven to get there.
Ignition on, or started for a second. Once primed, the fuel system has pulled petrol from the tank up to your filter and the lines. Normally little more than clearing, cleaning and sorting your filter, so still simple.
Driven a couple of miles. Now your pump has spent those miles running on thinned fuel. Tank, lines, filter, then clean fuel put through the entire circuit: that's this work, and the way your car was driven counts as much as the mileage. Driving the kids to the local primary school is one kind of trip. Very different a second time: a run to Newport, under 15 miles away, or some miles on the M4, under 10 miles from Oakdale, where your engine never stopped labouring hard.
It protested, and only then stopped: smoke, rattling, a throttle gone soft, an idle gone ragged. That's the motor telling you its fuel has stopped acting like diesel. Leave it wherever it has stopped: a lay-by, a side street, the verge on Penmaen Avenue. A vehicle pulled over early very rarely has lasting damage, because the fuel drain and the flush, which still come first, sort it out.
What Oakdale people 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 — that tank simply holds more of the same mixture. Percentage isn't how a diesel fuel system copes with petrol, whatever that advice presumes.
"Current diesels can handle a little petrol" — a myth, and closer to the opposite. At higher pressure, through smaller components: that is how a current diesel moves its fuel, so the protection matters for more, not less.
This is the one that fools drivers. Myth: "If it starts and drives, there's no damage done." The driver of a petrol motor fed diesel usually stops, since it will not run, and the harm stops with them. A diesel fed petrol normally starts, idles and drives away as though nothing has happened, while your pump grinds. Running is not the same as fine.
Myth: a two-stroke additive lets you to drive home. It was an old workaround, meant for another problem. It does not put back what petrol has thinned, and the petrol is still in your tank afterwards.
The next start sends petrol back round the pump out of the fuel lines and the filter, where some of it ends up after your engine has been run. That is why draining the tank yourself does not sort it — a myth. And, a can of petrol filled at the roadside is truly dangerous.
Why petrol in a diesel happens so easily
No one does it on purpose, and it is seldom carelessness. The forecourt makes it simple: the petrol nozzle is the slimmer of the two, and it slides into a diesel filler with almost no resistance, while a diesel nozzle mostly won't go into a petrol motor at all. So the slip runs one way.
When routine and your car stop matching, it takes place. A motor that's new to you — hired, on loan as a courtesy car, or brand new. Households running one of each, petrol and diesel. A forecourt you know, only with its pumps laid out differently. A train to catch, and a rushed fill on the way to Newbridge. Precisely the moment it takes place: after years of driving petrol, someone fills a diesel Volkswagen Passat for the first time. Throw in a back seat full of kids, a phone call or rain, and habit wins.
Oakdale people: how to prevent petrol in a diesel next time
- Check the pump, not the colour. In the UK unleaded handles are generally green and diesel black, yet not on every forecourt. The label is what counts.
- The first fill in an unfamiliar motor is the time to check your filler flap — inside it, or on the cap, plenty of cars state which fuel they take.
- A coloured fob or a sticker on the diesel's key achieves more than any amount of meaning to remember, for a house with one of each.
- It seems silly and it does the trick: on your first fill in a new or hired car, say "diesel" out loud before you take the nozzle off the petrol pump.
- While you're thinking about something else, this is an easy mistake to make — so put your phone away.
- Some diesels come with a filler built to reject a petrol nozzle, and devices you can add are available for vehicles without one. Such an inhibitor helps up to a point — as a backstop, not a reason to stop reading the petrol pump.
- Stop as soon as you realise. Less petrol in the tank makes a thinner blend. It doesn't change what to do next, which is still not to fire it up.
Already put petrol in a diesel around Oakdale?
In that case, there is only a short order of things. Leave it unstarted, with the ignition switched off too. The attendants on the forecourt — whether at the nearest petrol station itself or wherever you filled up — will normally help roll it away from the petrol pump if you ask. Then call 0333 366 0103 and tell us what was put in, roughly how much, and whether it has run.
Corrosion and deposits form the trouble with AdBlue, whereas petrol means lost protection. So if it was AdBlue, say so — and read its own Oakdale page.
Oakdale petrol in a diesel jobs: why one costs more than another
Four different jobs lie behind the four situations above — which is why there is no fair single price. What shifts the cost is chiefly which of them you are in. Beyond that it is the share — how much petrol was put in against how much that tank holds — and after that where the car is and whether our van can reach it safely.
What got in, how much, and if it's run — three questions our engineers ask before costing, not after, for precisely that reason. The answers turn a range into a straight figure.
About Oakdale, briefly
Oakdale is a village in Caerphilly, situated on the banks of a river at an elevation of 248 metres. Oakdale has a mix of housing types, but is predominantly characterised by terraced homes. Oakdale is located near other small communities such as Croespenmaen and Pentref-y-groes, and is within commuting distance of Newport, the nearest city.
Fuel drain cover across Caerphilly, Oakdale included
Petrol in diesel jobs in Oakdale — part of the NP postcode area — go to vans that likewise cover the places around it, Croespenmaen, Pentref-y-groes and Rock among them. No need to move the car to us. Forecourts, supermarket car parks, lay-bys and your own drive are all places we drain.
In Oakdale and still at the pump?
Nothing beats it: that's where you are. Call, and leave it switched off.