Llandough: Put Petrol in a Diesel Car?
With your tank still holding the petrol and the engine not yet started, almost every job takes only a drain, so keep your engine off. That outcome is decided in the minutes straight after the fill-up, and not by the amount that got in. Across Llandough and the remainder of The Vale of Glamorgan, Petrol in Diesel drains the vehicle and flushes it where it sits, whether by a roadside, on a private drive or at a forecourt. Phone before all else happens, and you'll hear what happens next.
What to try now about petrol in a diesel
- While you drive, your pump and the fuel injectors wear. This is why you do not fire it up, and why you don't depend on it once it has started. The trick about petrol in a diesel in particular — the point people get wrong — is that it drives away fine for the first mile or two. Diesel in a petrol motor normally can't run at all, which stops the motorist and stops the damage with them. This one lets you keep going.
- Two things, diesel: it ignites, and on the way through it keeps your injection pump and injectors lubricated. Petrol only manages the one. Which is why the ignition remains off too — switch it on and you frequently prime your system, and that is petrol exiting that tank for exactly those components.
- Topping up clears nothing. It gives you a larger tank of the same mixture, since a diesel fuel system does not cope with petrol by percentage the way that guidance assumes — so don't pour diesel on top to water down it. Octane is beside the point too: super unleaded is petrol.
- A motor that hasn't moved is the quickest one to handle, and so wait where you are if you reasonably can. Pulled up on the verge on Willowmere? Hazards on, then leave the vehicle there. An odd place suits us better than a started motor.
- Before you dial, work out your location. Anything next to you with a sign on it, plus a postcode starting CF64 2 — that is what settles whether our van turns up or circles.
- What went in, approximately how much, and also if your car has fired — those three facts determine the whole visit. Phone 0333 366 0103 then tell us.
The high-pressure fuel pump spent that morning commute labouring on a fluid that had shed a lot of the protection it is built around. Diesel greases that pump, and the injectors with it, before any of the fuel combusts; petrol does the burning and none of the protecting. So imagine a diesel Renault Megane, filled at quarter past eight, taken in to work, and left standing at Cogan until the penny drops somewhere around eleven. Three hours of standing have changed nothing about it. The couple of miles before that did a lot, which is why the question we ask is about mileage not hours. Call us. Leave it exactly where it is.
If you have put petrol in the diesel Skoda Octavia in Llandough and you are now stranded outside Total Asia Food with a boot loaded with shopping, ring us. Do not crank it once more to get out of that bay. We'll come out to you, clear your tank, clean the fuel lines and put new diesel in so you can get home. A mile or so at light throttle uses hardly any fuel, so these tend to be the simple ones.
Here's the entire mechanism. Diesel needs enough body to seal the close tolerances it goes through, and petrol takes that away. That is it. Which explains the usual King George V Memorial Playing Fields call — a diesel Audi A3, out there without fuss and back down on power, rough at idle, perhaps a bit of smoke. Injection systems work hydraulically as well as chemically, and so the fuel has to hold pressure and not just burn; weakened, it leaks past those gaps instead of building, and delivery comes weaker, later, less even than your engine was engineered about. Not a failing motor, though. Fuel that has stopped behaving like diesel. Put that right and it stops.
Phoning from near St Dochdwy's Church? Three things help us. The filler — which side of your car it's on. Room for a van beside you, without the road being blocked. And if anything has run since the fill-up. The spot itself hardly matters: on-street is where our technicians work most, and we would far rather have a cramped spot than a motor someone has driven somewhere simpler. Then it's a drain for the Vauxhall Astra, a filter change where there is one worth changing, lines cleaned, fresh fuel put round the entire circuit. By now the worst of that is in the fuel lines and not your tank.
Hire car or company car? Phone them before you ring us — some agreements want the hire firm to approve the work, and sorting that out first is a great deal quicker than sorting it after that. Then call us about the Mercedes A-Class by Llandough War Memorial Hall, and don't worry that you can't say how full the tank was. Nearly no one can, in a car they picked up two days ago, and we work it out on the spot. The reason our engineers ask is that petrol in a diesel does its harm as a proportion: the same few litres in a nearly empty tank is a far stronger blend than in a full one. Petrol is rated on how well it withstands igniting under pressure, which is the opposite of what a diesel needs — so the stronger the mix, the more it knocks, smokes and goes flat.
Draining petrol from the diesel on a forecourt
The job begins at a forecourt, usually. Frequently the job wraps up there too. We work on station forecourts routinely, with the station's agreement, so if you are still at Asda that is generally where this drain takes place.
Before your motor has run — a forecourt is the only setting this ends up spotted. Fuel drawn out of the tank and through the fuel filter, right to your high-pressure pump, is what happens when the motor is started and the vehicle is moved to where it is now: the car park, the drive or the lay-by, anywhere other than the forecourt. So the flush takes in the filter and your lines along with the tank. That is still not a calamity, and we deal with it where the car sits. What determines it is whether the ignition was turned in the seconds after your receipt was checked.
The staff will normally happily wheel the vehicle out from the petrol pump so the next motorist can get by. That's worth doing. Firing the car to move four vehicle lengths is not.
Llandough and the towns near it
Llandough is a residential suburb, so our team are out to it and to anywhere by it on the usual journeys: Penarth Moors, Cogan, Penarth Flats, Leckwith and Grangetown.
If yours isn't on that list it doesn't mean we do not come — there are separate pages for most places around The Vale of Glamorgan, and the ones mentioned above are just the nearest neighbours. Near a border, or somewhere a satnav can't find? Ring us to ask rather than assuming.
The ground this page spans sits on this map. We work at the roadside, on forecourts, on driveways and in car parks throughout all of it, and the car does not need to come to us.
Stopped at the roadside somewhere in Llandough?
Not everyone finds a suitable spot to pull over. A normal call for us instead of an odd one: noticed after setting off, landed by the verge on Llandough Hill or at a lay-by with the hazard lights flashing.
Okay where you are? Wait beside it. Not okay? Move out and away from it. Don't fire up your motor to nurse the vehicle somewhere handier — a diesel running on petrol will often oblige, and every mile it obliges for is drawing the mixture further into the fuel system. However inconvenient the spot, it is no bother for us to come to it, and that is a lot better for the car than driving on.
Petrol in a diesel, but the car has moved
Your M4 is the road that matters now, and sits under 10 miles from Llandough. Some distance along, and onto it in the first place: a misfuelled diesel will usually do both before anything seems wrong. What you get then is seldom a tidy stop. Power ebbs away, the idle goes uneven, and there may be some smoke.
Never restart it to move it. Pull off at the first sensible exit then turn off. It alters what our engineers bring, and so mention it when you phone: on a longer run — anything approaching the under 3 miles to the nearest city — take it the petrol has been through your filter, your pump and the injectors.
Llandough itself
Llandough is a suburban area in The Vale of Glamorgan, situated near the coast and approximately 2 miles from Cardiff. Llandough has a relatively low elevation of 38 metres and is close to nearby places such as Penarth Moors and Cogan. Llandough is predominantly composed of flat housing, which is typical of many coastal areas in Wales. Llandough is also relatively close to the city of Cardiff, with easy access to its amenities.
What our technicians do when our engineers reach you around Llandough
- Our technicians ask first, price after. What got in? How much? Has your engine run? Those replies alter what the work really is.
- The contaminated fuel is pulled out of your tank.
- What is left in the system shouldn't be what created the issue, so your fuel lines get cleaned and the filter cleared.
- The fuel system gets bled, on clean diesel.
- The motor is started and tested to confirm it runs correctly on new diesel.
The car is then ready for you to drive away. Our engineers do everything wherever your car has ended up, which means it never needs to be taken to a garage, and when it has been spotted early, it is very uncommon for there to be permanent damage.
AdBlue in a diesel tank in Llandough is a distinct job
The issue is not the same, though the opening rule is — do not fire it up — if what went in was AdBlue rather than petrol. Diluted diesel, and no lubrication left for the system that relies on it. That is petrol. AdBlue is urea in water, and in a diesel tank it leads to rust and residue in its place.
AdBlue removal around Llandough has a page of its own with the full story on it, including why it is frequently the more significant of the two. We handle both.
Paying for a petrol-in-diesel fuel drain in Llandough
What shifts the figure is listed below, as this job isn't one job and our engineers cannot truthfully put a single price on this page.
- Whether the motor has been run or driven. This is the big one.
- The tank's capacity, set against how much of the wrong fuel went into it.
- Which got in: petrol or AdBlue.
- Whether a technician can sensibly get to the vehicle and work on it, which rests on where your vehicle is.
A clear answer rather than a range is what you get for telling us three things: the car, the amount, and if it has run. For the car at home that is going nowhere and is not time-critical, is fine too.
Questions our technicians get about petrol in diesel around Llandough
At a petrol station around Llandough, can you do a fuel drain there?
Yes, and it is where a big share of this work takes place. Our engineers visit Morrisons and the other forecourts locally all the time, with the station's consent — tell us which one you are at when you phone and we'll tell you whether our engineers can work there.
A couple of litres of petrol in a diesel — too much?
Proportion decides it rather than litres — and more than either, whether the motor has run. Five litres into an almost dry tank isn't five into a full one, no. But both land on the same question in the end: has that mixture been drawn right through, or has it not?
Already driven it with petrol in your diesel? What now?
Stop sensibly. Off. Nothing after that. Driving is what moves the trouble from that tank into the pump and injectors — but it's salvageable a lot more commonly than people assume, and the single most useful thing you can do now isn't restart the car.
My warranty — does a fuel drain void it?
A manufacturer's warranty outlasts a drain then flush done to a proper standard, which is no change at all. A disagreement over a warranty is likelier to come from running a diesel on petrol — so leave it turned off.
Adding two-stroke oil, then driving home
No. Two-stroke oil is an old workaround for a different problem and it does not replace what petrol has weakened. The pump still has to put up with it, as the tank still has petrol in it later on.
Main dealers and petrol in a diesel
You don't need one. The car is drained and cleaned wherever it is, with no need to bring it to a dealership.
Still with the vehicle?
Your engine stays off.
Driven it already? Then somewhere sensible, stop, switch off, and no restarting it afterwards. Cold, stationary, going nowhere: that's the best position to be in. People fear this far more than they need to.
Throughout The Vale of Glamorgan and in Llandough: on-site fuel draining, at home or on the forecourt or at the kerbside.