Kimpton: Petrol in a Diesel Car? How Worried to Be
Probably less than you already are — provided nobody has started it. Petrol resting in a diesel tank does nothing to the engine until something pulls it through your fuel system — your ignition priming the pump, the starter, or the drive on its own. So the honest answer to the first query anyone in Kimpton asks, "have I ruined it?", is normally no. To leave the car that way, call Petrol in Diesel and leave the engine switched off. The remainder of this page sets out what petrol really does to a diesel, how to judge how far it has got, and how to make sure it does not happen to you again.
The engine and petrol in a diesel: what happens
Passing through an engine, diesel is doing two things at once. Before it ignites, it protects — then it ignites. The high-pressure fuel pump and the fuel injectors are made to extremely fine clearances, and your diesel passing through them is what keeps those surfaces from wearing against one another.
Petrol does the first task badly and the second not at all. A pump running on a petrol mix is wearing itself out, since petrol is thinner than diesel and takes away the lubrication your fuel system depends on. Petrol is also designed to resist igniting under compression — the opposite of what a diesel needs from its fuel — and that's where any rattling starts.
Seen together, they make clear what shape the problem takes. Contact does not do the damage — circulation does. Any tank with petrol in it is a fuel issue. Whatever a worn pump sheds travels on, borne by your fuel, into the injectors further along, which is why a pump that has been working on that petrol is where a mechanical problem begins.
Four scenarios our technicians see around Kimpton: how serious is petrol in a diesel?
Fuelled but not once started — the best it gets. Being on a forecourt is what makes this the case: elsewhere, your car has been driven there to begin with. With the petrol kept in the tank alone, it is drained and cleaned on the spot, and nothing more is needed.
A moment's running, or just your ignition on. With the fuel system primed, your lines and filter already contain petrol that has come from the tank. Still usually simple: drain, flush, and the fuel filter sorted.
Your pump has worked a few miles on diluted fuel — that is what driving the car does. Tank, lines, filter, then fresh fuel put through the whole system: that is this work, and the way the car was driven matters as much as the miles. On the school run to Kimpton Primary School, the miles is small. Very different a second time: a run to St Albans, under 10 miles away, or some mileage on the A1(M), under 5 miles from Kimpton, where the motor never stopped labouring hard.
It protested, and only then stopped: smoke, rattling, a throttle gone soft, an idle gone uneven. The motor is telling you your fuel is no longer acting like diesel. Stop where you are — on the verge on Claggy Road, at the kerb, down a side road — and do not move it. Lasting damage is very uncommon if a car is stopped early, and the fuel drain and flush that still go first deal with it.
Stories Kimpton motorists hear about petrol in a diesel
"Top it up the rest of the way with diesel and it will be fine" — a myth. It will not. Nothing is removed when you top up — the tank simply carries more of the same blend. Percentage is not how a diesel fuel system tolerates petrol, whatever that advice supposes.
Myth: "A newer diesel can cope with a bit of petrol." If anything, the reverse. Protection counts more on newer diesels, not less, because their fuel passes through smaller parts at higher pressure.
The myth that catches motorists off guard: if it starts and drives, it must be unharmed. Diesel in a petrol motor generally leaves a motor that won't run: the motorist stops, and so does the damage. A diesel fed petrol generally starts, ticks over and drives away as though nothing has happened, whilst your pump grinds. Being able to run is not proof of being fine.
An outdated fix for a separate fault is behind this one. Myth: "Add some two-stroke oil and drive the car home." It does not put back what petrol has weakened, and that petrol is still inside the tank after that.
If the motor has run, part of the petrol is in your filter and your lines, not the tank — and your next start pulls it straight back through the pump. So the myth "drain that tank yourself and you are sorted" doesn't stand up. On top of that, petrol emptied into a can by the road is truly risky.
How it happens: petrol in a diesel
Nobody does it on purpose, and it is rarely carelessness. The forecourt makes it simple: the petrol nozzle is the narrower of the two, and it slides into a diesel filler with almost no resistance, whilst a diesel nozzle mostly won't go into a petrol vehicle at all. So the slip runs one way.
When habit and your car stop matching, it takes place. A new car, a hire car or a courtesy car. Two vehicles on one driveway, one petrol, one diesel. Your normal forecourt, its pumps now in a different order. A hurried fill on the way to Harpenden with a train to catch. Years of petrol cars behind you, a diesel Peugeot 308 in front of you at the forecourt for its first tank — that's when. With rain, a call coming in, or children to deal with, your hand simply does what it has always done.
Kimpton people: how to avoid petrol in a diesel next time
- The label is what matters, and so check the petrol pump instead of the colour: in the UK unleaded handles are normally green and diesel black, but not on each forecourt.
- In a car you do not know, look inside the flap over your filler or at the cap before your first fill: plenty of cars print the fuel there.
- A coloured fob or a sticker on the diesel's key achieves more than any amount of intending to remember, for a household with one of each.
- Say it before you lift it. On your first fill in a new or hired car, say "diesel" out loud before you take the nozzle off the pump. It sounds silly and it works.
- Whilst you're thinking about something else, this is an easy mistake to make — so put the phone away.
- Some diesels come with a filler designed to refuse a petrol nozzle, and devices you can add are available for vehicles without one. Such an inhibitor helps up to a point — as a safety net, not a reason to stop checking the petrol pump.
- Noticing it halfway? Stop at once. A thinner mixture results from less petrol in the tank, yet the next step stays the same: do not crank it.
Already put petrol in a diesel in Kimpton?
In that case, there's just a short order of things. Never fire it up, and don't switch the ignition on. Ask the attendants to help you roll it clear of the petrol pump if you are still on the forecourt, whether that's Esso or somewhere else. Phone 0333 366 0103 next, with three answers — your fuel, the approximate volume, and if it's run.
AdBlue, not petrol? Then say so. Corrosion and deposits, not lost protection, make it a separate problem — Kimpton has a page all for it.
Why one petrol in a diesel task around Kimpton costs more than another
The four scenarios above are four different tasks, so no single quote for this would be honest. Mostly, your cost moves with which situation you're in. The share counts next, meaning how much of that tank is petrol, and then the position of your car and whether getting to it is safe for a technician.
That's why our technicians ask three questions before pricing instead of after: what went in, how much, and whether it has run. With those replies, you get a straight figure rather than a range.
About Kimpton and where it is
Kimpton is a village in Hertfordshire, situated approximately 24.9 miles north of London and 7 miles east of St Albans. Kimpton sits in a rural area at an elevation of around 89 metres, surrounded by nearby places such as Blackmore End, Ansells End, and Porters End. Kimpton has a population of around 1546 people, predominantly living in semi-detached housing.
Fuel drain cover across Hertfordshire, Kimpton included
Blackmore End, Ansells End and Porters End are among the places near Kimpton that the same vans work, answering petrol in diesel call-outs across Kimpton's SG postcode area. No need to move the vehicle to us. Forecourts, supermarket car parks, lay-bys and your own driveway are all places where we work.
At the petrol pump around Kimpton, still?
No position is better: that's where you are. Turned off it stays; then phone.