How Worried Should You Be? Petrol in a Diesel Car in Seven Sisters
Less than you probably are, provided it has not been started. "Have I ruined it?" is the first thing everyone around Seven Sisters asks, and the honest answer is usually no, since petrol left in a diesel tank hurts nothing until it is drawn through your fuel system — by ignition priming, by your starter, or by being driven. Keep it like that: leave your engine off then ring Petrol in Diesel. The remainder of this page sets out what petrol actually 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.
Inside the engine: what petrol in a diesel does
Two tasks fall to diesel on its journey through a motor. It protects first, and only then does it burn. Your high-pressure pump and the fuel injectors are built to very fine tolerances, and your diesel passing through them is what stops those surfaces from wearing against each other.
Poorly at the first, not at all at the second: that is petrol. It's runnier than diesel and strips away the protection the system rests on, and so a pump running on a petrol mixture is a pump wearing itself. And petrol is made to resist igniting under compression, which is the opposite of what a diesel needs from its fuel. That's where the rattling comes from.
Taken together, they show what shape the issue takes. It is circulation that causes the damage, not contact. Petrol in a tank is a fuel fault. Whatever a worn pump sheds goes on, borne by the fuel, into your injectors further along, which is why a pump that has worked on the petrol is where a mechanical problem begins.
Four scenarios our engineers see in Seven Sisters: how bad is petrol in a diesel?
Filled up, never started. The best case there can be. On a forecourt, and genuinely only there, the petrol is still confined to your tank — since anywhere else your car was driven to reach it. The job is emptying and rinsing on the spot.
Your ignition switched on, or a brief start. The fuel system has been primed, and so petrol has left the tank and got to the filter and the lines. Usually nothing more than draining, purging and sorting the filter, and so still easy.
Driven a couple of miles. Now the pump has spent these miles running on thinned fuel. How hard your car was driven counts as much as how far, and the work covers your tank, your lines, the fuel filter and fresh fuel through the entire system. Driving the children to Earlsmead Primary School is one kind of trip. Any mileage on the M11, under 5 miles from Seven Sisters, means the motor working hard throughout, and a run to London, under 5 miles away, makes a very different task as well.
It protested, and only then stopped: smoke, knocking, a throttle gone soft, an idle gone lumpy. That's your engine telling you its fuel no longer is behaving like diesel. Stop where you are — on the verge on Stonebridge Road, at the kerb, down a side road — and don't move it again. A car pulled over quickly very rarely has long-term damage, because the fuel drain and the flush, which still go first, deal with it.
Petrol in a diesel myths Seven Sisters motorists hear
Myth: "Fill it the rest of the way with diesel and it will be fine." It will not. A fuller tank of the same mix is all it gives, because topping up takes out nothing. A diesel fuel system does not tolerate petrol by percentage in the way that guidance supposes.
Myth: "A newer diesel can cope with a bit of petrol." If anything, the opposite. Protection counts more on modern diesels, not less, because their fuel passes through finer components at higher pressure.
Myth: "If it starts and drives, there is no damage done." This is the one that fools people. A petrol motor fed diesel generally won't run, so the driver stops and the harm stops with them. Nothing seems to have happened when a diesel fed petrol fires up, ticks over and drives away, which it usually will; meanwhile your pump wears. Running does not mean fine.
An old fix for a separate fault lies behind this one. Myth: "Add some two-stroke oil and drive the car home." None of what petrol diluted gets put back by it — and later, your tank still contains the petrol.
Myth: "Drain that tank yourself and you're sorted." After your engine has been run, some of the petrol is no longer inside your tank: it's in the fuel filter and your lines, and it goes straight back through the pump on the next start. Clearing petrol into a can by the roadside is also genuinely risky.
Petrol in a diesel: how does it take place?
On purpose? Never. Through carelessness? Rarely, if ever. The petrol nozzle is the narrower 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.
When routine and your car stop matching, it happens. Hire cars, courtesy cars, and motors that are new to you. Households running one of each, petrol and diesel. Your ordinary forecourt, its pumps now in a different order. A train to catch, and a rushed fill on the way to the nearest station. A new-to-you diesel Volkswagen Golf, its first fuelling, and a motorist used to petrol: precisely when it happens. With rain, a call arriving, or a car full of children to deal with, the hand just does what it has always done.
Preventing petrol in a diesel next time you fill up in Seven Sisters
- The label is what matters, so read the petrol pump instead of the colour: in the UK unleaded handles are normally green and diesel black, yet not on each forecourt.
- Many cars state the fuel type inside your filler flap or on the cap, and so check there on your first fill in any vehicle you don't know.
- Good intentions count for less than a sticker or a fob in a bright colour on your diesel's key when a household has one of each. So mark it.
- "Diesel", out loud, before you pick up the nozzle — each time a new or hired car needs its first tank. It seems silly. It does the trick.
- Tuck the phone away. This is an easy mistake to make while you're thinking about something else.
- Some diesels come with a filler designed to reject a petrol nozzle, and devices you can add are available for cars without one. Such an inhibitor helps up to a point — as a backstop, not a reason to stop reading the pump.
- Noticing it halfway? Stop there and then. A thinner mixture results from less petrol inside the tank, but your next stage stays the same: don't start it.
Put petrol in a diesel in Seven Sisters already?
The order of things is brief, then. Leave it unstarted, with your ignition switched off as well. Yet on the forecourt, at Esso or anywhere else? Ask the staff to help you roll the vehicle away from the pump. Then ring 0333 366 0103 and tell us what went in, about how much, and whether it has run.
Say so if it was AdBlue instead of petrol: it is a separate problem, with its own page for Seven Sisters, because AdBlue brings corrosion and deposits instead of lost lubrication.
One petrol in a diesel task in Seven Sisters costs more than another. Why?
Four different jobs sit behind the four situations above — which is why there's no fair single price. Chiefly, the cost shifts with which one you're in. The proportion counts next, meaning how much of that tank is petrol, and then the location of the car and whether getting to it is safe for a van.
What went in, how much, and whether it has run — three questions we ask before pricing, not after, for precisely that reason. The answers turn a range into a straight figure.
About Seven Sisters, briefly
Seven Sisters is a suburban area in north London, situated near the River Lea and close to Tottenham Green, South Tottenham, and Tottenham. Seven Sisters has a relatively low elevation of around 15 metres above sea level, reflecting its riverside setting. Seven Sisters is characterized by a high proportion of flat dwellings, which dominate the local housing stock. Seven Sisters is located approximately 5.7 miles from central London, making it a popular residential area for commuters.
Across Greater London and around Seven Sisters: fuel drain cover
Seven Sisters rests in the N postcode area, and our vans that answer petrol in diesel call-outs there work the places around it as well — Tottenham Green, South Tottenham and Tottenham among them. Our technicians drain wherever your vehicle is — your own drive, a lay-by, a supermarket car park, a forecourt — so it does not have to come to us.
Still at the pump around Seven Sisters?
Then you are in the best place there is. Phone, and leave it turned off.