Should You Worry? Petrol in a Diesel Car in Lewsey Farm
Not started? Then less anxious than you likely are. "Have I ruined it?" is the first thing anyone in Lewsey Farm asks, and the truthful answer is generally no, because petrol resting in a diesel tank harms nothing till it is drawn through the fuel system — by ignition priming, by your starter, or by driving. Leave your engine off and ring Petrol in Diesel — that keeps it like that. What petrol actually does to a diesel, how to judge how far it has gone, and how to keep it from happening a second time: that is the rest of this page.
The engine and petrol in a diesel: what happens
Diesel has two jobs on its way through a motor. Lubricating comes before burning; it does both. The high-pressure fuel pump and the fuel injectors are built to extremely fine tolerances, and the diesel passing through them is what keeps those surfaces from grinding against one another.
The second task petrol does not do at all, and the first it does poorly. A pump working on a petrol mixture is wearing itself out, because petrol is thinner than diesel and strips out the lubrication your fuel system relies on. Petrol is also made to resist igniting under compression — the opposite of what a diesel needs from its fuel — and that's where any rattling comes.
Together, those leave the shape of the problem plain. It is movement that causes the harm, not contact. Any tank with petrol in it is a fuel problem. Whatever a worn pump sheds goes on, carried by the fuel, into the injectors downstream, which is why a pump that has been working on the petrol is where a mechanical fault starts.
How bad is petrol in a diesel? Four scenarios we see around Lewsey Farm
The best case there can be: filled up, not once started. The petrol is in the tank and just that tank, and the task is a drain and a flush where the vehicle sits. This is the one situation that can only truly happen on a forecourt, because anywhere else your car has been driven to get there.
The ignition turned on, or a short start. Your system has been primed, and so petrol has left your tank and reached your filter and the lines. Still usually easy: drain, flush, and the filter sorted.
Those few miles driven meant your pump labouring on fuel thinned by petrol the whole way. The work is the tank, the lines, the fuel filter and clean fuel through the whole system, and how hard the vehicle was driven counts as much as how far. On the school run to St Martin De Porres Catholic Primary School, the mileage is small. A run as far as St Albans, under 15 miles away, is a very different job. So is any miles on the M1, under a mile from Lewsey Farm, where the engine has been working hard throughout.
It complained, and only then stopped: smoke, knocking, a throttle gone soft, an idle gone ragged. What you are hearing is your motor signalling fuel that no longer acts like diesel. Whether it is the verge on Peregrine Road, a lay-by or a side street, stop there and leave it. Long-term damage is very rare if a vehicle is stopped soon, and the drain and flush that still go first deal with it.
Lewsey Farm motorists and the petrol in a diesel stories they hear
"Top it up the rest of the way with diesel and it will be fine" — a myth. It won't. Topping up takes out nothing; it gives you a bigger tank of the same mix. Percentage isn't how a diesel fuel system tolerates petrol, however much that advice supposes.
"Current diesels can handle a little petrol" — a myth, and nearer the opposite. Protection matters more on newer diesels, not less, since their fuel passes through smaller parts at higher pressure.
This is the one that fools people. Myth: "If it starts and drives, there is no damage done." Any petrol motor fed diesel generally won't run, so the motorist stops and the harm stops with them. Nothing seems to have happened when a diesel fed petrol fires up, ticks over and drives away, as it usually will; meanwhile your pump wears. Running is not the same as fine.
An old fix for a different fault 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 the petrol.
The next start sends petrol back round your pump from your lines and the fuel filter, where some of that sits once the engine has run. That is why a DIY tank drain doesn't sort it — a myth. On top of that, petrol cleared into a can by the road is truly risky.
Petrol in a diesel: how does it happen?
It is rarely carelessness, and nobody does it on purpose. A diesel nozzle generally will not fit a petrol motor, but the narrower petrol nozzle goes into the filler of a diesel almost without resistance — so forecourts make this one error straightforward, and only in one direction.
When habit and the car stop matching, it occurs. Hire cars, courtesy cars, and cars that are new to you. A household with one petrol and one diesel on the drive. Your normal forecourt, its pumps suddenly in a different order. A hurried fill en route to Leagrave with a train to catch. Exactly the moment it happens: after years of driving petrol, a driver fills a diesel Volkswagen Golf for the first time. Throw in rain, a phone call or a back seat full of children, and your hand does what it has always done.
Next time you fill up around Lewsey Farm: avoiding petrol in a diesel
- Read the pump, not the colour. In the UK unleaded handles are normally green and diesel black, but not on each forecourt. The label is what counts.
- Many cars state the fuel inside the filler flap or on the cap, so check there on your first fill in a vehicle you don't know.
- A coloured fob or a sticker on your diesel's key achieves more than any amount of meaning to remember, in a home with one of each.
- Say it before you lift it. On the first fill in a new or hired car, say "diesel" aloud before you take the nozzle off the pump. It sounds silly and it does the trick.
- Mistakes like this are straightforward to make whilst your mind is on something else, so the phone goes away.
- A misfuel inhibitor helps, up to a point. Some diesels have a filler designed to reject a petrol nozzle, and add-on devices are available for vehicles without one. They are a safety net, not a reason to stop checking the petrol pump.
- Less petrol means a weaker mix, so stop the moment you notice — though remembering that the next stage is unchanged. It's still not to start the vehicle.
Already put petrol in a diesel in Lewsey Farm?
Short and simple, then, is the order of things. Do not turn the ignition on, and do not fire it up. Ask the staff to help you push it clear of the petrol pump if you are still on the forecourt, whether that's Shell or somewhere else. Next, 0333 366 0103. We will ask what went in, about how much, and if it's been run.
Corrosion and deposits are the problem with AdBlue, where petrol brings lost lubrication. So if it was AdBlue, say so — and see its own Lewsey Farm page.
Why one petrol in a diesel job around Lewsey Farm costs more than another
Four separate jobs lie behind the four situations above — which is why there is no fair single price. What shifts your cost is mostly which of them you're in. The ratio matters next, meaning how much of your tank is petrol, and then the location of the vehicle and whether getting to it is safe for a van.
Three queries come first, before any quote, instead of after — what was put in, how much, has it run — and this is the reason. Those answers turn a range into a straight figure.
About Lewsey Farm and its setting
Lewsey Farm is a suburban area in Bedfordshire, situated near the River Lea and characterised by semi-detached housing. Lewsey Farm sits at an elevation of 133 metres, with nearby open spaces including Houghton Park. Lewsey Farm is located near other residential areas such as Parkside and Leagrave, and is approximately 12 miles from St Albans. Lewsey Farm has a population of around 9133 people, making it a sizable community within the region.
Fuel drain cover around Lewsey Farm and across Bedfordshire
Our teams answering petrol in diesel call-outs in Lewsey Farm, in the LU postcode area, also work the places near it, Houghton Park, Parkside and Leagrave included. No need to move the vehicle to us. Forecourts, supermarket car parks, lay-bys and your own driveway are all spots where we work.
At the pump in Lewsey Farm, still?
The best spot there is, then — that's where you are. Keep the car switched off, then ring.