Riverhead: Petrol in a Diesel Car? How Worried to Be
Likely less than you are now — as long as nobody has started it. Everyone in Riverhead starts with "have I ruined it?", and the honest answer is generally no: petrol left in your tank of a diesel stays harmless till priming, cranking or driving pulls it into the system. Keep it that way: leave your engine off then phone Petrol in Diesel. The remainder of this page covers 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.
Petrol in a diesel: what does it do to the motor?
Two tasks fall to diesel on its route through a motor. It protects to begin with, and only then does it burn. Built to extremely fine tolerances, the injectors and your pump depend on the diesel flowing through them to stop their surfaces wearing against one another.
Petrol handles the first job badly and the second not at all. The rattling comes from petrol being made not to ignite when compressed, which is exactly the reverse of what a diesel needs. On top of that it is thinner than diesel, it strips away the protection the system hinges on, and any pump working on such a mix is wearing itself.
The shape of the problem is clear once you put those together. It's movement that does the harm, not contact. Any tank with petrol in it is a fuel issue. Whatever a worn pump sheds travels on, borne by the fuel, into the fuel injectors further along, which is why a pump that has been working on that petrol is where a mechanical problem starts.
Riverhead, petrol in a diesel: four cases, from mild to major
The best case there can be: filled up, never started. At a forecourt, and really only there, that petrol is still limited to the tank — because anywhere else the vehicle was driven to reach it. The task is draining and rinsing on the spot.
Your ignition turned on, or a brief start. With the fuel system primed, the lines and filter now contain petrol that has come from the tank. Normally little more than clearing, purging and seeing to the fuel filter, and so still easy.
Driven a few miles. Now your pump has spent those miles running on diluted fuel. The work is that tank, the fuel lines, the fuel filter and fresh fuel through the entire circuit, and how hard the vehicle was driven counts as much as how far. On the school run to Riverhead Infants' School, the miles is short. Any distance on the M26, under a mile from Riverhead, means the motor working hard throughout, and a run to London, under 25 miles away, is a very different job too.
Rattling, a lumpy idle, smoke, a throttle gone soft: driven till it complained. The engine is telling you your fuel is no longer acting like diesel. Stop wherever you are — the verge on Chesterfield Drive, a lay-by, a side street — then leave the car there. The fuel drain and flush-through still go first, and they deal with it: if a car is stopped early, lasting damage is very unusual.
What Riverhead people get told about petrol in a diesel — and the stories in it
It will not be fine. The myth: "Fill it the rest of the way with diesel and it'll be." A bigger tank of the same mix is all you get, because topping up takes out nothing. The idea behind the advice — that diesel fuel systems accept petrol by percentage — is wrong.
If anything, the opposite is true. Myth: "A modern diesel can cope with a bit of petrol." Lubrication matters more on newer diesels, not less, since their fuel passes through finer components at higher pressure.
The myth that catches motorists out: if it starts and drives, it must be unharmed. Feed diesel to a petrol engine and it generally won't run, so the driver stops — and the damage stops with them. Nothing looks to have happened when a diesel fed petrol fires up, ticks over and drives away, as it usually does; meanwhile your pump wears. Being able to run isn't proof of being fine.
Myth: "Add some two-stroke oil and drive the car home." It is an old workaround for a distinct issue. None of what petrol weakened gets put back by it — and later, your tank still holds that petrol.
Myth: "Drain the tank yourself and you are sorted." Once your engine has been run, some of that petrol is no longer inside the tank: it is in the fuel filter and your lines, and it goes straight back through your pump at your next start. Emptying petrol into a can at the kerbside is also genuinely risky.
How does petrol in a diesel happen?
A careless moment is seldom the cause, and no one means to do it. A diesel nozzle generally will not go into a petrol vehicle, yet the narrower petrol nozzle goes into the filler of a diesel almost without resistance — so forecourts make this one mistake easy, and just in one direction.
The moment habit stops matching the car is the moment it occurs. Any vehicle that is new to you — hired, on loan as a courtesy car, or brand new. One petrol and one diesel on the drive of the same household. The pumps in a different order on a well-known forecourt. Filling up in a rush on the way to Dunton Green, with a train to catch. Exactly the moment it occurs: after years of driving petrol, a driver fills a diesel Renault Megane for the first time. With rain, a call arriving, or children to deal with, your hand simply does what it has always done.
Riverhead drivers: how to avoid petrol in a diesel next time
- Not every forecourt in the UK keeps to green for unleaded and black for diesel, even if most generally do. Read the petrol pump's label; the colour is just a clue.
- In a motor you don't know, look inside the flap over your filler or at the cap before your first fill: plenty of cars print the fuel there.
- One of each in the house? Label the key to your diesel — a coloured fob, a sticker — since intending to remember is not enough.
- "Diesel", aloud, before you lift the nozzle — each time a new or hired car gets its first tank. It seems daft. It works.
- Mistakes like this are easy to make whilst your mind is on something else, so your phone goes away.
- Add-on devices exist for motors without one, and some diesels come with a filler that won't take a petrol nozzle. Useful — but a backstop only, never a reason to stop checking the label.
- Less petrol means a thinner mix, so stop the moment you realise — while remembering that the next step is unchanged. It is still not to crank it.
Petrol already in a diesel around Riverhead? Begin here
The order of things is short, then. Starting it is out, and so is turning on the ignition. Yet on the forecourt, at Tesco or anywhere else? Ask the attendants to help you push it clear of the petrol pump. Next, 0333 366 0103. We'll ask what went in, about how much, and if it's been run.
Say so if it was AdBlue rather than petrol: it is a separate issue, with its own page for Riverhead, since AdBlue brings corrosion and deposits instead of lost protection.
Riverhead petrol in a diesel jobs: why one costs more than another
The four scenarios above are four different tasks, so no single quote for this would be honest. Which of them you are in is chiefly what shifts the cost. After that it's the share — how much petrol was put in against how much that tank takes — and after that where the car is and whether a van can reach it safely.
What went in, how much, and if it's run — three queries our engineers ask before pricing, not after, for precisely that reason. A range turns into a straight figure once those replies are in.
About Riverhead and its setting
Riverhead is a suburban area in Kent, situated lakeside with a mix of housing types, predominantly detached homes. Riverhead sits at an elevation of 78 metres, close to the nearby places of Longford, Chipstead, and Bessels Green. Riverhead is located approximately 19.9 miles from London, making it a commuter-friendly area. Riverhead has a population of around 4654 residents, living in a variety of detached homes.
Across Kent and around Riverhead: fuel drain cover
Longford, Chipstead and Bessels Green are among the places near Riverhead that the same teams work, answering petrol in diesel calls across Riverhead's TN postcode area. The vehicle does not need to move to us: our engineers drain at a forecourt, in a supermarket car park, in a lay-by or on your own driveway.
Riverhead: still at the pump?
In that case, you could not be in a better position. Turned off it remains; then phone.