Should You Worry? Petrol in a Diesel Car in Lamellion
Unstarted? Then less anxious than you likely are. "Have I wrecked it?" is the first thing everyone in Lamellion asks, and the truthful answer is usually no, because petrol resting in a diesel tank harms nothing until it's drawn through your fuel system — by ignition priming, by the starter, or by driving. Keep it that way: leave your engine off and ring Petrol in Diesel. Read on for three things: the effect petrol has inside a diesel engine, the clues of how far it has got, and ways to make sure you don't do it again.
Inside the motor: what petrol in a diesel does
On its way through a motor, diesel has two tasks. It lubricates to begin with, and after that does it burn. Made to extremely fine clearances, the injectors and the pump rely on the diesel flowing through them to stop their surfaces wearing against one another.
Poorly at the first, not at all at the second: that is petrol. The knocking comes from petrol being made not to ignite when compressed, which is precisely the opposite of what a diesel needs. On top of that it is thinner than diesel, it strips out the protection the system rests on, and any pump running on that blend is wearing itself.
Together, those make the shape of the issue plain. Not contact but movement is what does the damage. Where the petrol is only inside the tank, it's a problem of fuel, nothing more. Whatever a worn pump sheds goes on, carried by your fuel, into the injectors further along, which is why a pump that has worked on that petrol is where a mechanical problem begins.
How bad is petrol in a diesel? Four scenarios our engineers see around Lamellion
Fuelled up, not once started. The best case there can be. Being at a forecourt is what makes this the case: elsewhere, the vehicle has been driven there to begin with. With the petrol held in that tank alone, it is emptied and rinsed on the spot, and nothing more is needed.
Your ignition switched on, or a brief start. With the system primed, the lines and filter already contain petrol that came from your tank. Drain, flush, see to your filter: still usually straightforward.
Driven a couple of miles. Now your pump has spent these miles working on diluted fuel. How hard your car was driven counts as much as how far, and this work takes in your tank, your lines, the filter and fresh fuel through the entire circuit. Short trips, such as the school run to Liskeard Hillfort Primary School, are one thing. Getting as far as Plymouth, under 25 miles away, makes a very different job — as does any miles on the M5, under 50 miles from Lamellion, with the motor running hard all the way.
Knocking, a lumpy idle, smoke, a throttle gone soft: driven till it complained. What you are hearing is your motor reporting fuel that no longer behaves like diesel. Leave it wherever it stops: a lay-by, a side street, the verge on B3254. Long-term damage is very unusual when a car is pulled over soon, and the fuel drain and flush that still come first take care of it.
Myths Lamellion drivers hear about petrol in a diesel
Myth: topping up to full with diesel makes it fine. It does not. Nothing is removed by topping up — you're left with a bigger tank, still the same mix. Percentage isn't how a diesel fuel system tolerates petrol, whatever that guidance assumes.
If anything, the reverse is true. Myth: "A modern diesel can cope with a bit of petrol." At higher pressure, through finer components: that is how a modern diesel moves its fuel, so the lubrication matters for more, not less.
Myth: "If it starts and drives, there's no damage done." This is the one that catches motorists. Feed diesel to a petrol engine and it normally will not run, and so the motorist stops — and the damage stops with them. A diesel fed petrol normally starts, ticks over and drives away as if nothing has happened, while your pump grinds. Fine and running aren't the same thing.
An old fix for a different fault is 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, the tank still holds that petrol.
The next start sends petrol back round the pump out of the lines and the fuel filter, where some of it ends up once the motor has been run. That's why draining the tank yourself doesn't leave you sorted — a myth. On top of that, petrol cleared into a can by the road is genuinely hazardous.
How petrol ends up: petrol in a diesel
A careless moment is seldom the cause, and nobody means to do it. The petrol nozzle is the smaller of the two and slides into a diesel filler with almost no resistance; a diesel nozzle mostly won't go into a petrol car at all. The forecourt makes it simple, and the error runs one way.
It happens when habit and the vehicle stop matching. A new vehicle, a hire car or a courtesy car. Two motors on one driveway, one petrol, one diesel. The pumps in a different order on a well-known forecourt. Rushing for a train at Liskeard and filling up en route. A new-to-you diesel Renault Megane, its first fuelling, and a motorist accustomed to petrol: exactly when it happens. With rain, a call coming in, or a car full of children to deal with, your hand simply does what it has always done.
Preventing petrol in a diesel next time you fill up in Lamellion
- Not every forecourt in the UK follows green for unleaded and black for diesel, even if most usually do. Check the pump's label; the colour is only a hint.
- Plenty of motors state the fuel type inside the filler flap or on the cap, and so check it on your first fill in any vehicle you do not know.
- A coloured fob or a sticker on the diesel's key does more than any amount of intending to remember, for a household with one of each.
- "Diesel", aloud, before you lift the nozzle — each time a new or hired car needs its first tank. It seems silly. It does the trick.
- Whilst you're thinking about something else, this is an easy mistake to make — so tuck your phone away.
- A misfuel inhibitor helps, up to a point. Some diesels come with a filler built to block 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.
- Stop the moment you notice. Less petrol in the tank makes a thinner mix. It does not change what to do next, which is still not to crank it.
Already put petrol in a diesel around Lamellion?
Then the order of things is brief. Do not switch the ignition on, and don't crank it. The attendants on the forecourt — whether at Morrisons itself or wherever you filled up — will usually help roll it away from the pump if you ask. Next, 0333 366 0103. We'll ask what went in, about how much, and if it has been run.
AdBlue, not petrol? Then say so. Corrosion and deposits, not lost protection, make it a separate problem — Lamellion has a page just for it.
Why one petrol in a diesel job around Lamellion costs more than another
There is no fair single quote for this, because the four scenarios above are four different jobs. Which of them you are in is mostly what moves the cost. Two things come after that: the petrol that went in as a proportion of what the tank holds, then the spot the vehicle is in and whether our van can reach it safely.
Before any quote, not after, come three queries: your fuel that went in, the quantity, and if it has run. That is why. Given those answers, you get a straight figure instead of a range.
About Lamellion itself
Lamellion is a small locality in Cornwall, situated on the riverside at an elevation of 102 metres. Lamellion lies near the towns of Liskeard and Looe Mills, and is close to Moorswater. Lamellion has a population of around 681 people, predominantly living in semi-detached housing. Lamellion is located approximately 15.5 miles from Plymouth and 202.8 miles from London.
Fuel drain cover around Lamellion and across Cornwall
Lamellion rests in the PL postcode area, and the teams that answer petrol in diesel jobs there work the spots near it as well — Moorswater, Liskeard and Looe Mills among them. The vehicle does not need to move to us: our technicians drain at a forecourt, in a supermarket car park, in a lay-by or on your own driveway.
Still at the petrol pump in Lamellion?
Nothing beats it: that's where you now are. Keep it off. Ring.