How Worried Should You Be? Petrol in a Diesel Car in Short Cross
Likely less than you already are — as long as no one has started the vehicle. "Have I wrecked it?" is the first question everyone in Short Cross asks, and the truthful answer is normally no, since petrol left in a diesel tank harms nothing till it is dragged through the fuel system — by ignition priming, by the starter, or by driving. Petrol in Diesel is who to call, with the engine left off, so it stays that way. The remainder of this page explains what petrol actually does to a diesel, how to tell how far it has got, and how to make sure it does not happen to you again.
Petrol in a diesel: what does it do to the engine?
On its way through a motor, diesel does two tasks. Oiling comes before burning; it does both. Made to extremely fine gaps, the fuel injectors and your pump rely on your diesel moving through them to stop their surfaces wearing against one another.
The second task petrol doesn't do at all, and the first it does poorly. The knocking comes from petrol being made not to ignite when compressed, which is precisely the reverse of what a diesel needs. On top of that it is thinner than diesel, it strips away the protection the system rests on, and any pump running on such a mixture is wearing itself.
Put those together and the shape of the issue is plain. Contact does not do the damage — circulation does. Where that petrol is only in your tank, it's a problem of fuel, nothing more. A pump that has been labouring on that petrol is the start of a mechanical one, and whatever a worn pump sheds travels on with the fuel to the injectors further on.
Four scenarios we see in Short Cross: how serious is petrol in a diesel?
Fuelled, and not started: nothing beats it. Only the tank has petrol in it, so the task is clearing your tank and cleaning the fuel system where the vehicle stands. This scenario can only really take place at a forecourt: anywhere else, your car got there by being driven.
A moment's running, or just the ignition on. Petrol has left that tank and got to your filter and the lines, because the fuel system has been primed. That is usually still an easy task — a drain, a flush, and the filter seen to.
Driven a few miles. Now your pump has spent those miles labouring on weakened fuel. The work is the tank, the fuel lines, the filter and clean fuel through the entire circuit, and how hard the vehicle was driven counts as much as how far. A school run to Newfield Park Primary Academy is one matter. Driving as far as Birmingham, under 10 miles away, makes a very different job — as does any miles on the M5, under 3 miles from Short Cross, with your engine labouring hard all the way.
Driven on until it protested — rattling, smoke, an uneven idle, a dead throttle. The engine is telling you your fuel is no longer behaving like diesel. Pull up where you are — on the verge on Shelah Road, at the kerb, down a side road — and don't move it. Permanent damage is very uncommon if a car is pulled over soon, and the drain and flush-through that still go first take care of it.
Petrol in a diesel myths Short Cross motorists hear
"Top it up the rest of the way with diesel and it'll be fine" — a myth. It will not. Topping up takes out nothing; it gives you a bigger tank of the same mixture. A diesel fuel system doesn't tolerate petrol by percentage in the way that guidance assumes.
Myth: "A current diesel can cope with a bit of petrol." If anything, the opposite. At higher pressure, through finer components: that's how a newer diesel moves its fuel, and so the protection counts for more, not less.
Myth: "If it starts and drives, there is no damage done." This is the one that catches drivers. The driver of a petrol motor fed diesel normally has no choice but to stop, because it will not run, and the damage stops with them. While the pump wears, a diesel fed petrol usually starts, idles and drives away as if nothing has happened. Running is not the same as fine.
Myth: "Add some two-stroke oil and drive the car home." It's an old fix for a distinct problem. It does not put back what petrol has diluted, and the petrol is still inside that tank later.
If your engine has been run, part of the petrol sits in your filter and the lines, not the tank — and the next start sends it right back through the pump. So the myth "drain that tank yourself and you're sorted" doesn't stand up. Also, a can of petrol drained by the roadside is genuinely hazardous.
Petrol in a diesel: how does it happen?
Nobody does it on purpose, and it's seldom carelessness. The forecourt makes it simple: the petrol nozzle is the smaller of the two, and it slides into a diesel filler with almost no resistance, while a diesel nozzle mostly won't go into a petrol vehicle at all. So the mistake runs one way.
When routine and the car stop matching, it happens. A new vehicle, a hire car or a courtesy car. A household with one petrol and one diesel on the drive. A familiar forecourt with the pumps in a different order. Filling up in a rush on the way to Old Hill, with a train to catch. Exactly the moment it happens: after years of driving petrol, a driver fills a diesel Volkswagen Golf for the first time. Throw in a back seat full of kids, a phone call or rain, and the hand takes over.
Preventing petrol in a diesel next time you fill up around Short Cross
- Check the petrol pump, not the colour. In the UK unleaded handles are generally green and diesel black, but not on each forecourt. The label is what counts.
- Inspect the filler flap. Plenty of vehicles state the fuel type inside the flap or on the cap. Look at it on your first fill in any vehicle you do not know.
- Mark your key. In a home with one of each, a coloured fob or a sticker on the diesel's key does more than any amount of meaning to remember.
- It sounds silly and it does the trick: on your first fill in a new or hired car, say "diesel" out loud before you lift the nozzle off the pump.
- Thinking about something else is when this becomes an easy mistake to make, so tuck your phone away then keep your mind on the petrol pump.
- Some diesels come with a filler built to refuse a petrol nozzle, and devices you can add exist for motors without one. Such an inhibitor helps up to a point — as a backstop, not a reason to stop checking the pump.
- Noticing it mid-fill? Stop there and then. A weaker mix follows from less petrol in the tank, but your next step remains the same: don't fire it up.
Already put petrol in a diesel in Short Cross?
The order of things is short, then. Leave it unstarted, with the ignition off too. Still at the forecourt, at BP or anywhere else? Ask the staff to help you push the vehicle away from the pump. Next, 0333 366 0103. We'll ask what went in, roughly how much, and if it's been run.
If it was AdBlue instead of petrol, say so. That's a separate fault — corrosion and deposits and not lost protection — and it has its own page for Short Cross.
What makes one Short Cross petrol in a diesel job cost more than the next
The four scenarios above are four different jobs, so no single quote for this would be fair. Which of them you are in is mostly what moves your cost. Beyond that it is the share — how much petrol was put in against how much that tank takes — and then where your car is and whether our van can reach it safely.
Before any quote, not after, come three questions: your fuel that went in, its volume, and whether it's run. That is why. Those answers are what change a range into one firm number.
About Short Cross, for a moment
Short Cross is a locality situated on the riverside in the West Midlands, with an elevation of around 138 metres. Short Cross lies approximately 6.5 miles from Birmingham and is near other places such as Hawne, Halesowen, and Coombeswood. Short Cross has a population of around 1757 people and predominantly consists of semi-detached housing. Short Cross is located about 105 miles northwest of London.
Short Cross and West Midlands: where our fuel drain cover runs
Petrol in diesel calls in Short Cross — part of the B postcode area — go to vans that likewise cover the places round it, Hawne, Halesowen and Coombeswood among them. The vehicle does not need to move to us: our technicians drain on a forecourt, in a supermarket car park, in a lay-by or on your own drive.
Still at the pump around Short Cross?
No position is better: that is where you now are. Keep the vehicle switched off, then ring.