Petrol in a Diesel Car in Treherbert: How Worried Should You Be?
Not started? Then less worried than you probably feel. Everyone in Treherbert starts with "have I wrecked it?", and the fair answer is generally no: petrol resting inside the tank of a diesel remains harmless until priming, cranking or driving pulls it into the system. To keep it that way, phone Petrol in Diesel then leave the engine switched off. What petrol actually does to a diesel, how to judge how far it has travelled, and how to keep it from happening a second time: that is the rest of this page.
Petrol in a diesel: what does it do to the motor?
Passing through a motor, diesel does two jobs at once. Lubricating comes before burning; it does both. Made to extremely fine gaps, the injectors and the pump rely on the diesel moving through them to stop their surfaces wearing against one another.
Poorly at the first, not at all at the second: that is petrol. It is thinner than diesel and strips away the lubrication your fuel system rests on, so a pump running on a petrol mixture is a pump wearing itself. And petrol is made to resist igniting under compression, which is the reverse of what a diesel needs from its fuel. That is where the knocking comes from.
The shape of the problem is plain once you put those together. It is circulation that does the damage, not contact. All a tank with petrol in it amounts to is a fuel problem. Whatever a worn pump sheds goes on, borne by your fuel, into the injectors downstream, which is why a pump that has been working on the petrol is where a mechanical fault starts.
Four scenarios our technicians see in Treherbert: how serious is petrol in a diesel?
Filled up, and not started: no case is better. On a forecourt, and truly only there, that petrol is still limited to that tank — because everywhere else the vehicle was driven to reach it. The task is emptying and cleaning on the spot.
Your ignition switched on, or a short start. With the fuel system primed, the fuel lines and filter now contain petrol that has come from that tank. Drain, flush, see to the filter: still normally easy.
Those few miles on the road meant your pump labouring on fuel weakened by petrol the whole way. The work is that tank, the fuel lines, your filter and fresh fuel through the whole circuit, and how hard the vehicle was driven matters as much as how far. A school run to the local primary school is one thing. Getting as far as Swansea, under 25 miles away, makes a very different job — as does any mileage on the M4, under 10 miles from Treherbert, with the motor labouring hard all the way.
It complained, and only then stopped: smoke, rattling, a throttle gone soft, an idle gone ragged. The engine is telling you the fuel is no longer behaving like diesel. Whether it is the verge on Station Street, a lay-by or a side road, stop where you are then leave it. Long-term damage is very rare if a car is pulled over soon, and the drain and flush that still come first deal with it.
Petrol in a diesel myths Treherbert motorists hear
It will not be fine. The myth: "Fill it the rest of the way with diesel and it'll be." A fuller tank of the same mix is all you get, because topping up takes out nothing. Percentage isn't how a diesel fuel system tolerates petrol, whatever that advice assumes.
If anything, the reverse holds. Myth: "A newer diesel can cope with a bit of petrol." Finer parts and higher pressure are how a modern diesel runs its fuel, and that makes the lubrication matter more, not less.
Myth: "If it starts and drives, there's no damage done." This is the one that catches people. The motorist of a petrol engine fed diesel normally has no choice but to stop, since it will not run, and the damage stops there. A diesel fed petrol normally starts, idles and drives away as though nothing has happened, while your pump grinds. Running doesn't mean fine.
An old fix for a separate problem lies 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 afterwards, your tank still holds that petrol.
If your engine has been run, part of that petrol is in your filter and your lines, not your tank — and the next start sends it straight back through the pump. So the myth "drain that tank yourself and you're sorted" does not stand up. On top of that, petrol drained into a can by the road is genuinely risky.
Petrol in a diesel: how does it take place?
A careless moment is rarely the cause, and no one means to do it. The forecourt makes it easy: the petrol nozzle is the slimmer of the two, and it slides into a diesel filler with almost no resistance, whilst a diesel nozzle mostly will not go into a petrol vehicle at all. So the error runs one way.
It occurs when habit and the vehicle stop matching. A motor that is new to you — a hire car, on loan as a courtesy car, or brand new. Two vehicles on one driveway, one petrol, one diesel. Your usual forecourt, its pumps now in a different order. A rushed fill on the way to the nearest station with a train to catch. Precisely the moment it takes place: after years of driving petrol, a driver fills a diesel Renault Clio for the first time. Throw in rain, a phone call or a back seat full of kids, and your hand repeats what it has always done.
Next time you fill up in Treherbert: preventing petrol in a diesel
- The label is what matters, and so check the petrol pump rather than the colour: in the UK unleaded handles are usually green and diesel black, yet not on every forecourt.
- In a car you don't know, look inside the flap over your filler or at the cap before the first fill: plenty of cars state the fuel there.
- Label your key. In a house with one of each, a coloured fob or a sticker on your diesel's key does more than any amount of intending to remember.
- It seems daft and it works: on the first fill in a new or hired car, say "diesel" out loud before you take the nozzle off the petrol pump.
- Put the phone away. This is an easy mistake to make whilst you are thinking about something else.
- A misfuel inhibitor helps, up to a point. Some diesels come with a filler built to reject a petrol nozzle, and add-on devices are available for vehicles without one. They are a backstop, not a reason to stop reading the pump.
- Less petrol means a weaker mixture, and so stop as soon as you realise — while remembering that the next step is unchanged. It's still not to crank it.
Treherbert: already put petrol in a diesel?
The order of things is brief, then. Leave it unstarted, with the ignition switched off as well. If you are still at the forecourt — Texaco or anywhere else — ask the staff to help you roll it clear of the pump. Next, 0333 366 0103. We will ask what got in, about how much, and if it's been run.
Say so if it was AdBlue instead of petrol: it is a separate problem, with its own page for Treherbert, because AdBlue brings corrosion and deposits rather than lost lubrication.
Treherbert petrol in a diesel jobs: why one costs more than another
There's no fair single price for this, because the four scenarios above are four different jobs. Chiefly, the cost shifts with which situation you're in. Where the car is matters too, and whether a technician can safely reach it, after the ratio of petrol to what the tank takes.
That is why we ask three queries before quoting instead of after: what got in, how much, and whether it has run. Their answers are what change a range into one firm number.
About Treherbert and where it is
Treherbert is a town situated in the Rhondda Valley in south Wales, on the banks of the River Rhondda. Treherbert sits at an elevation of 188 metres, surrounded by hills and nearby communities such as Pen-yr-englyn and Tynewydd. Treherbert is characterized by its predominantly terraced housing and riverside location, with the town of Swansea located approximately 18 miles to the west. Treherbert is a relatively small town, with a population of around 5678 people.
Fuel drain cover around Treherbert and across Rhondda Cynon Taf
Petrol in diesel jobs around Treherbert — part of the CF postcode area — go to vans that also cover the places round it, Pen-yr-englyn, Tynewydd and Ynyswen among them. No need to move your car to us. Forecourts, supermarket car parks, lay-bys and your own driveway are all places where we work.
Still at the pump in Treherbert?
In that case, you couldn't be in a better position. Keep it off. Ring.