How Worried Should You Be? Petrol in a Diesel Car in Horsell
Provided it has not been started, you can worry far less than you likely are. Till the ignition primes the pump, the starter turns, or the vehicle is driven, petrol in a diesel tank simply sits there and does nothing. Which means the truthful reply to that first Horsell query — "have I ruined it?" — usually no. Petrol in Diesel is who to phone, with the engine left off, so it stays that way. The rest 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 again.
What petrol in a diesel does to the engine
Two tasks fall to diesel on its journey through a motor. It ignites, and before it combusts it protects. Your high-pressure pump and the injectors are made to very fine clearances, and the diesel passing through them is what keeps those surfaces from wearing down against each other.
The second job petrol does not do at all, and the first it does poorly. The knocking comes from petrol being designed 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 lubrication your system depends on, and any pump working on such a mixture is wearing itself.
Taken together, they make clear what shape the problem has. Not contact but movement is what does the damage. Where the petrol is only in the tank, it is an issue 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 fuel injectors further on.
Horsell, petrol in a diesel: four situations, from mild to serious
The best case there is: filled up, not once started. Just your tank has petrol in it, so the job is draining your tank and flushing the system where the car stands. This scenario can only truly take place on a forecourt: anywhere else, the vehicle got there by being driven.
The ignition turned on, or a short start. Petrol has left the tank and got to the filter and your lines, because the fuel system has been primed. Drain, flush, deal with your filter: still usually simple.
The pump has spent a few miles on weakened fuel — that's what driving the car does. How hard your car was driven matters as much as how far, and the work takes in your tank, the fuel lines, the fuel filter and clean fuel through the entire circuit. On the school run to The Horsell Village School, the mileage is small. Driving as far as Westminster, under 25 miles away, makes a very different task — as does any mileage on the M3, under 5 miles from Horsell, with the motor running hard all the way.
Driven on until it protested — knocking, smoke, a lumpy idle, a soft throttle. The engine is telling you the fuel is no longer acting like diesel. Pull up on the spot — on the verge on Wilson Way, at the kerb, down a side road — and don't move it. What comes first is still the drain and flush-through, and that sorts it out, with permanent damage very uncommon if a vehicle is stopped early.
Horsell drivers and the petrol in a diesel stories they hear
"Top it up the rest of the way with diesel and it will be fine" — a myth. It will not. Nothing is removed by topping up — you are left with a bigger tank, still the same mixture. Percentage is not how a diesel fuel system tolerates petrol, however much that advice supposes.
If anything, the reverse holds. Myth: "A newer diesel can cope with a bit of petrol." Smaller parts and higher pressure are how a modern diesel runs its fuel, and that makes the lubrication count more, not less.
Myth: "If it starts and drives, there is no damage done." This is the one that fools drivers. The driver of a petrol motor fed diesel usually stops, since it will not run, and the damage stops with them. Nothing seems to have happened when a diesel fed petrol fires up, ticks over and drives away, which 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 vehicle home." It's an outdated workaround for a distinct issue. It doesn't put back what petrol has weakened, and the petrol is still inside the tank after that.
The next start draws petrol back round your pump out of the fuel lines and your filter, where some of that ends up once the motor has been run. That's why a DIY tank drain doesn't leave you sorted — a myth. It's also genuinely hazardous to drain petrol into a can at the roadside.
Petrol in a diesel: how does it happen?
No one does it on purpose, and it is seldom carelessness. The petrol nozzle is the narrower of the two and slips 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 easy, and the mistake runs one way.
The moment routine stops matching the vehicle is the moment it happens. A vehicle that is new to you — hired, on loan as a courtesy car, or just bought. Households running one of each, petrol and diesel. A familiar forecourt with the pumps in a different order. Rushing for a train at Woking and filling up en route. Precisely the moment it occurs: after years of driving petrol, a driver fills a diesel Renault Clio for the first time. Your hand repeats what it has always done once you add rain, a phone call or a back seat full of kids.
How to prevent petrol in a diesel at your next fill-up in Horsell
- The label is what matters, so check the pump instead of the colour: in the UK unleaded handles are normally green and diesel black, but not on each forecourt.
- Check the filler flap. Many vehicles state the fuel inside the flap or on the cap. Look at it on the first fill in a car you don't know.
- A coloured fob or a sticker on the diesel's key achieves more than any amount of intending to remember, for a house with one of each.
- Say it before you lift it. On the first fill in a new or hired car, say "diesel" out loud before you take the nozzle off the petrol pump. It sounds silly and it works.
- Put the phone away. This is an easy mistake to make while you are thinking about something else.
- A misfuel inhibitor helps, up to a point. Some diesels come with a filler designed to refuse a petrol nozzle, and add-on devices exist for cars without one. They are a backstop, not a reason to stop checking the petrol pump.
- Less petrol makes a weaker mix, and so stop the moment you notice — though remembering that the next stage is unchanged. It's still not to crank it.
Already put petrol in a diesel in Horsell?
Short and simple, then, is the order of things. Do not turn the ignition on, and don't fire it up. Ask the attendants to help you roll it away from the pump if you are still at the forecourt, whether that is Morrisons or somewhere else. Next, 0333 366 0103. We will ask what got in, about how much, and if it's been run.
AdBlue, not petrol? Then say so. Corrosion and deposits, not lost lubrication, make it a separate fault — Horsell has a page all for it.
What makes one Horsell petrol in a diesel job cost more than the next
A fair single price doesn't exist here: four situations, four separate jobs. Which of them you are in is chiefly what shifts the cost. The proportion counts next, meaning how much of the tank is petrol, and then the location of your car and whether reaching it is safe for our van.
Ahead of any quote, not after, we ask three questions: the fuel that was put in, its volume, and whether it has run. That is why. A range becomes a straight figure when those replies are in.
About Horsell, briefly
Horsell is a suburban area in Surrey, situated near the River Wey and characterised by its predominantly detached housing stock. Horsell sits at an elevation of around 35 metres, with nearby Woking and Mount Hermon providing local amenities. Horsell is located approximately 23 miles from London, with good transport links to the capital and surrounding areas like Horsell Birch.
Horsell and Surrey: where our fuel drain cover reaches
Our vans answering petrol in diesel call-outs around Horsell, in the GU postcode area, also work the spots near it, Woking, Mount Hermon and Horsell Birch included. You need not move the vehicle to us. Forecourts, supermarket car parks, lay-bys and your own driveway are all locations where we work.
In Horsell and still at the petrol pump?
The best position there is, then — that's where you are. Keep the car switched off, and ring.