Southrepps: Petrol in a Diesel Car? How Worried to Be
Far less than you probably are, provided it hasn't been started. Everyone around Southrepps begins with "have I ruined it?", and the honest answer is generally no: petrol left inside that tank of a diesel stays harmless till priming, cranking or driving pulls it into the system. Petrol in Diesel is who to ring, with the engine kept off, so it remains that way. The remainder of this page explains 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 a second time.
What petrol in a diesel does to the motor
Two jobs fall to diesel on its journey round a motor. It lubricates first, and only then does it burn. What stops the surfaces inside the high-pressure fuel pump and the fuel injectors from wearing down against each other is your diesel passing through them — they are made to very fine gaps.
Of these two tasks, petrol manages the first poorly and the second never. A pump working on a petrol mixture is wearing itself out, since petrol is runnier than diesel and takes away the protection the fuel system relies on. Petrol is also designed to resist igniting under compression — the opposite of what a diesel needs from its fuel — and that's where the knocking starts.
The shape of the trouble is plain once you put those together. It is circulation that does the harm, not contact. Where the petrol is only inside that tank, it's a fault of fuel, nothing more. A pump that has been working on that petrol is the start of a mechanical one, and whatever a worn pump sheds moves on with the fuel to the injectors further on.
Petrol in a diesel around Southrepps: how bad is it? Four situations
Filled but not once started — as good as it gets. The petrol is inside your tank and only the tank, and the job is a drain and a flush where the car stands. This is the one scenario that can only really take place at a forecourt, because anywhere else your car has been driven to get there.
Started for a second, or just the ignition on. Once primed, the system has pulled petrol from your tank up to the filter and the fuel lines. Drain, flush, see to the fuel filter: still usually easy.
Those few miles driven were your pump running on fuel thinned by petrol throughout. Miles is only half of that; how hard it was driven counts equally. Either way the work runs to your tank, the lines, your filter and fresh fuel through the whole circuit. The school run to Antingham and Southrepps Primary School is one matter. Any miles on the M11, over 50 miles from Southrepps, means your engine working hard throughout, and a run to Norwich, under 25 miles away, makes a very different task too.
Rattling, a ragged idle, smoke, a throttle gone soft: driven till it complained. The fuel is not behaving like diesel any more, and your motor is telling you. Whether it is the verge on Long Lane, a lay-by or a side road, stop there then leave it. Lasting damage is very unusual when a vehicle is stopped quickly, and the fuel drain and flush that still go first sort it out.
Southrepps motorists and the petrol in a diesel myths they hear
It will not be fine. The myth: "Fill it the rest of the way with diesel and it'll be." Nothing is removed by topping up — you are left with a fuller tank, still the same mixture. A diesel fuel system does not accept petrol by percentage in the way that advice assumes.
"Current diesels can handle a little petrol" — a myth, and nearer the reverse. Protection matters more on current diesels, not less, since their fuel passes through smaller parts at higher pressure.
"It starts, it drives, so no harm done" — the myth that catches most motorists than any other. Any petrol engine fed diesel usually won't run, so the driver stops and the damage stops with them. A diesel fed petrol generally starts, idles and drives away as if nothing has happened, whilst your pump grinds. Running isn't the same as fine.
An outdated workaround for a different issue is behind this one. Myth: "Add some two-stroke oil and drive the car home." None of what petrol weakened gets put back by it — and later, that tank still contains the petrol.
"Drain it yourself and you're sorted" — a myth, because after it has been running some petrol sits in your filter and lines, waiting to go straight back through your pump at the next start. Emptying petrol into a can at the roadside is also truly dangerous.
How petrol ends up: petrol in a diesel
Nobody does it on purpose, and it is rarely carelessness. The petrol nozzle is the slimmer of the two and slides into a diesel filler with almost no resistance; a diesel nozzle generally won't go into a petrol motor at all. The forecourt makes it easy, and the mistake runs one way.
It takes place when routine and the vehicle stop matching. Courtesy car, hire car, or a car that's brand new. Two motors on one drive, one petrol, one diesel. A well-known forecourt with the pumps in a different order. Fuelling up in a hurry en route to Gunton, with a train to catch. A new-to-you diesel Volkswagen Golf, its first fuelling, and a motorist accustomed to petrol: precisely when it happens. Throw in rain, a phone call or a back seat full of kids, and your hand repeats what it has always done.
Southrepps motorists: how to prevent petrol in a diesel next time
- Read the pump, not the colour. In the UK unleaded handles are generally green and diesel black, yet not on each forecourt. The label is what counts.
- The first fill in an unfamiliar motor 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 home? Mark the key to the diesel — a coloured fob, a sticker — because meaning to remember is not enough.
- Say it before you lift it. On your first fill in a new or hired car, say "diesel" aloud before you lift the nozzle off the pump. It seems silly and it works.
- Thinking about something else is when this becomes an easy mistake to make, and so put your phone away then keep your mind on the petrol pump.
- Add-on devices are available for vehicles without one, and some diesels come with a filler that will not take a petrol nozzle. Helpful — but a backstop at best, never a reason to stop checking the label.
- The moment you realise, stop: less petrol in the tank means a weaker mixture. What to do next doesn't change, though — still don't fire it up.
Petrol already in a diesel in Southrepps? Start here
Then the order of things is brief. Leave it unstarted, with the ignition off too. If you're still at the forecourt — TotalEnergies or anywhere else — ask the attendants to help you push the vehicle away from the petrol pump. Then call 0333 366 0103 and tell us what was put in, roughly how much, and if it's run.
Say so if it was AdBlue instead of petrol: it is a separate fault, with its own page for Southrepps, because AdBlue brings corrosion and deposits rather than lost protection.
Why one petrol in a diesel task in Southrepps costs more than another
A fair single quote does not exist here: four situations, four separate jobs. What moves the cost is chiefly which of them you're in. Two things follow that: the petrol that was put in as a share of what the tank holds, then the spot the vehicle is in and whether our van can get to it safely.
That is why our technicians ask three questions before costing rather than after: what was put in, how much, and if it has run. Those replies turn a range into a straight figure.
About Southrepps and where it is
Southrepps is a small village in north Norfolk, situated near the coast and approximately 17 miles north of Norwich. Southrepps sits at an elevation of around 43 metres, with the village surrounded by rolling countryside and nearby settlements such as Upper Street and Thorpe Market. Southrepps has a population of around 598 people, with detached housing being the predominant type in the area. Southrepps is located about 113 miles from London, making it a relatively rural community in eastern England.
Across Norfolk and in Southrepps: fuel drain cover
Upper Street, Thorpe Market and Lower Street are among the spots around Southrepps that the same teams work, answering petrol in diesel calls across Southrepps's NR postcode area. The car doesn't need to come to us: our technicians drain on a forecourt, in a supermarket car park, in a lay-by or on your own driveway.
Still at the pump around Southrepps?
In that case, you couldn't be in a better place. Call, and leave it turned off.