Lufton: Petrol in a Diesel Car? How Worried to Be
If it hasn't been started, worry far less than you probably are. "Have I ruined it?" is the first thing everyone in Lufton asks, and the truthful answer is generally no, since petrol resting in a diesel tank harms nothing until it's dragged through the fuel system — by ignition priming, by your starter, or by driving. Leave the motor off and call Petrol in Diesel — that keeps it like that. What petrol really does to a diesel, how to judge how far it has travelled, and how to keep it from happening a second time: that's the remainder of this page.
Petrol in a diesel: what does it do to the motor?
On its way through an engine, diesel does two tasks. It combusts, and before it burns it lubricates. The high-pressure fuel pump and the fuel injectors are made to extremely fine clearances, and the diesel passing through them is what stops those surfaces from wearing against each other.
The second job petrol doesn't do at all, and the first it does badly. Being less viscous than diesel, petrol strips out the lubrication a fuel system needs, so a pump on the blend wearing itself. It is also made to resist igniting under compression — the opposite of what a diesel needs — which is where you hear the knocking.
Put these together and the shape of the trouble is clear. The harm is done by movement, not by contact. Any tank with petrol in it is a fuel issue. The beginning of a mechanical one is a pump that has been labouring on that petrol — and whatever a worn pump sheds moves on with your fuel to your injectors beyond it.
How bad is petrol in a diesel? Four scenarios our technicians see around Lufton
Fuelled but not once started — the best it gets. Being at a forecourt is what makes this the case: elsewhere, the car has been driven there to begin with. With the petrol kept inside your tank alone, it's emptied and rinsed on the spot, and nothing more is needed.
Started for a moment, or just the ignition on. Once primed, your system has drawn petrol from the tank up to the fuel filter and your lines. That is normally still a straightforward task — a drain, a flush, and the fuel filter seen to.
Those few miles on the road meant the pump labouring on fuel weakened by petrol the whole way. Mileage is only half of that; how hard it was driven counts just as much. Either way the work runs to your tank, your lines, the fuel filter and clean fuel through the entire circuit. Driving the children to Kingfisher Primary School is one kind of trip. A run as far as Wells, under 25 miles away, is a very different task. So is any mileage on the M5, under 25 miles from Lufton, where the motor has been labouring hard throughout.
It protested, and only then stopped: smoke, knocking, a throttle gone soft, an idle gone ragged. The motor is telling you the fuel is no longer acting like diesel. Whether it is the verge on Artillery Road, a lay-by or a side street, stop there and leave it. What comes first is still the drain and flush, and that deals with it, with permanent damage very unusual when a vehicle is pulled over early.
Myths Lufton people hear about petrol in a diesel
It will not be fine. The myth: "Fill it the rest of the way with diesel and it will be." Topping up takes out nothing; it gives you a bigger tank of the same mix. A diesel fuel system doesn't tolerate petrol by percentage in the way that guidance supposes.
Myth: "A modern diesel can cope with a bit of petrol." If anything, the opposite. More precise parts and higher pressure are the way a newer diesel runs its fuel, and that makes the protection matter more, not less.
"It starts, it drives, and so no harm done" — the myth that catches most motorists than any other. The motorist of a petrol motor fed diesel normally has no choice but to stop, because it will not run, and the harm stops with them. Feed petrol to a diesel and it generally fires up, ticks over and drives away like nothing has happened — all the while its pump is wearing. Being able to run isn't the same as being fine.
Myth: "Add some two-stroke oil and drive the car home." It's an outdated fix for a different fault. That petrol is still in the tank after that, and what it has thinned isn't put back.
Myth: "Drain that tank yourself and you're sorted." After the motor has been run, some of that petrol is no longer in your tank: it's in your filter and the lines, and it goes straight back through the pump at the next start. And, a can of petrol filled by the kerbside is genuinely risky.
How petrol ends up: petrol in a diesel
Nobody does it on purpose, and it's rarely carelessness. A diesel nozzle generally won't fit a petrol vehicle, yet the smaller petrol nozzle goes into the filler of a diesel nearly without resistance — so forecourts make this one error easy, and only in that direction.
The moment habit stops matching the car is the moment it occurs. A car that's new to you — a hire car, on loan as a courtesy car, or just bought. Two cars on one driveway, one petrol, one diesel. A forecourt you know, only with its pumps arranged differently. A hurried fill on the way to Yeovil Pen Mill with a train to catch. The first fill-up in a diesel Volkswagen Passat after years of driving petrol is exactly the moment it happens. Throw in a back seat full of kids, a phone call or rain, and habit wins.
Lufton people: how to avoid petrol in a diesel next time
- Check the pump, not the colour. In the UK unleaded handles are generally green and diesel black, but not on every forecourt. The label is what matters.
- The first fill in a new car is the time to check the filler flap — on it, or on the cap, plenty of cars state which fuel they take.
- One of each in the house? Mark the key to the diesel — a coloured fob, a sticker — because meaning to remember isn't enough.
- "Diesel", out loud, before you pick up the nozzle — each time a new or hired car needs its first tank. It seems silly. It works.
- Thinking about something else is when this becomes an easy mistake to make, so put your phone away then keep your mind on the pump.
- Up to a point, a misfuel inhibitor helps: some diesels come with a filler designed to refuse a petrol nozzle, and add-on devices exist for the rest. Treat it as a safety net, then keep checking the pump.
- Less petrol means a weaker blend, and so stop the moment you notice — while remembering that your next step is unchanged. It is still not to fire it up.
Lufton: already put petrol in a diesel?
Short and simple, then, is the order of things. Leave it unstarted, with the ignition switched off as well. Ask the staff to help you roll it away from the pump if you are still on the forecourt, whether that is Asda or somewhere else. What went in, about how much, and whether it has run: tell us that when you ring 0333 366 0103.
AdBlue, not petrol? Then say so. Corrosion and deposits, not lost protection, make it a different fault — Lufton has a page all for it.
Why one petrol in a diesel task around Lufton costs more than another
An honest single price doesn't exist here: four situations, four separate tasks. What shifts your cost is chiefly which of them you are in. After that it is the ratio — how much petrol got in against how much the tank takes — and then where the vehicle is and whether a van can reach it safely.
Ahead of any quote, not after, come three queries: the fuel that got in, the amount, and whether it has run. That's why. A range becomes a straight figure when the answers are in.
About Lufton
Lufton is a suburban area in inland Somerset, situated approximately 83 metres above sea level. Lufton lies near several nearby places, including Houndstone, Alvington, and Thorne Coffin, and is around 18 miles from the city of Wells. Lufton has a population of around 3665 people and is characterised by predominantly detached housing. Lufton is also located about 116.9 miles west of London.
Fuel drain cover across Somerset, Lufton included
Lufton sits in the BA postcode area, and our vans that answer petrol in diesel calls there work the locations around it as well — Houndstone, Alvington and Thorne Coffin among them. A forecourt, a supermarket car park, a lay-by or your own driveway are all locations our engineers drain, and the car does not need to come to us.
In Lufton and still at the pump?
Then you're in the best position there can be. Leave the vehicle turned off, then ring.