How Worried Should You Be? Petrol in a Diesel Car in Town Centre
Less than you probably are, if it hasn't been started. Everyone around Town Centre starts with "have I ruined it?", and the honest answer is normally no: petrol resting in that tank of any diesel remains harmless until priming, cranking or driving draws it into the system. To leave it like that, ring Petrol in Diesel then leave the motor switched off. The remainder of this page sets out 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 a second time.
The motor and petrol in a diesel: what goes on
Two tasks fall to diesel on its route round a motor. Lubricating comes before burning; it does both. What keeps the surfaces inside your high-pressure pump and the fuel injectors from grinding against one another is your diesel flowing through them — they are built to very fine tolerances.
Badly at the first, not at all at the second: that's petrol. Being less viscous than diesel, petrol strips away the protection a fuel system needs, leaving a pump on the mixture wearing itself. It is equally made to resist igniting under compression — the reverse of what a diesel needs — which is where you hear the clattering.
The shape of the trouble is plain when you put those together. Contact does not do the harm — movement does. A tank with petrol in it is a fuel fault. Whatever a worn pump sheds goes on, carried by your 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.
Town Centre, petrol in a diesel: four situations, from mild to major
Fuelled, and not started: no case is better. Just the tank has petrol in it, so the task is emptying the tank and cleaning your system where the vehicle sits. This situation can only truly take place on a forecourt: anywhere else, your car got there by being driven.
Started for a moment, or only your ignition on. Petrol has come out of that tank and got to the filter and the lines, because your system has been primed. Still normally simple: drain, flush, and your filter seen to.
Those few miles driven were your pump working on fuel weakened by petrol throughout. How hard the vehicle was driven counts as much as how far, and this work covers that tank, the fuel lines, your filter and fresh fuel through the entire system. On the school run to the local primary school, the mileage is small. Very different again: a trip to Edinburgh, under 10 miles away, or any miles on the M8, under 10 miles from Town Centre, where the motor never stopped working hard.
It protested, and only then stopped: smoke, knocking, a throttle gone soft, an idle gone uneven. The motor is telling you your fuel is no longer acting like diesel. Pull up where you are — on the verge on Croft Street, at the kerb, down a side road — and don't move it again. Permanent damage is very uncommon when a vehicle is pulled over soon, and the drain and flush that still go first take care of it.
Stories Town Centre drivers hear about petrol in a diesel
False: topping up to full with diesel makes it fine. It does not. Nothing is removed when you top up — that tank simply carries more of the same blend. The idea behind the advice — that diesel fuel systems tolerate petrol by percentage — is wrong.
Myth: "A newer diesel can cope with a bit of petrol." If anything, the opposite. At higher pressure, through more precise components: that is how a newer diesel moves its fuel, so the lubrication matters more, not less.
The myth that catches motorists off guard: if it starts and drives, it must be unharmed. The motorist of a petrol engine fed diesel usually has no choice but to stop, since it will not run, and the damage stops with them. A diesel fed petrol generally starts, ticks over and drives away as though nothing has happened, whilst your pump grinds. Fine and running are not the same at all.
Myth: "Add some two-stroke oil and drive the vehicle home." It is an outdated workaround for a distinct fault. None of what petrol weakened is put back by it — and later, the tank still contains the petrol.
"Drain it yourself and you are sorted" — a myth, because after it's been running some petrol sits in the fuel filter and lines, waiting to go straight back through the pump on your next start. Draining petrol into a can at the roadside is also really dangerous.
How does petrol in a diesel take place?
It is rarely carelessness, and no one does it on purpose. The forecourt makes it simple: the petrol nozzle is the smaller of the two, and it slips into a diesel filler with almost no resistance, while a diesel nozzle mostly won't go into a petrol car at all. So the mistake runs one way.
When habit and the vehicle stop matching, it happens. Hire cars, courtesy cars, and cars that are new to you. One petrol and one diesel on the driveway of the same household. Your ordinary forecourt, its pumps now in a different order. Rushing for a train at Curriehill and filling up en route. Years of petrol cars behind you, a diesel Volkswagen Golf in front of you on the forecourt for its first tank — that's when. Throw in rain, a phone call or a back seat full of kids, and the hand repeats what it has always done.
Next time you fill up around Town Centre: preventing petrol in a diesel
- Check the petrol pump, not the colour. In the UK unleaded handles are usually green and diesel black, but not on every forecourt. The label is what matters.
- Inspect your filler flap. Plenty of cars state the fuel type inside the flap or on the cap. Look at it on your first fill in any motor you do not know.
- Good intentions count for less than a sticker or a fob in a bright colour on your diesel's key when a home has one of each. So mark it.
- It seems silly and it works: on your first fill in a new or hired car, say "diesel" aloud before you lift the nozzle off the petrol pump.
- Thinking about something else is when this becomes an easy mistake to make, so tuck your phone away and keep your mind on the pump.
- Up to a point, a misfuel inhibitor helps: some diesels come with a filler built to block a petrol nozzle, and aftermarket devices are available for the remainder. Count it as a safety net, and keep checking the pump.
- As soon as you realise, stop: less petrol in the tank makes a weaker blend. What to do next doesn't change, though — still do not crank it.
Town Centre: already put petrol in a diesel?
The order of things is short, then. Leave it unstarted, with the ignition switched off as well. The staff on the forecourt — whether at Tesco itself or wherever you filled up — will normally help roll it away from the petrol pump if you ask. What got in, about how much, and if it has run: tell us those when you call 0333 366 0103.
If it was AdBlue instead of petrol, say so. That is a separate fault — corrosion and deposits instead of lost lubrication — and it has its own page for Town Centre.
One petrol in a diesel job around Town Centre costs more than another. Why?
The four situations above are four separate tasks, so no single quote for this would be fair. The scenario itself does most of the work of moving the cost. Beyond that it's the ratio — how much petrol went in against how much your tank holds — and after that where the vehicle is and whether a van can get to it safely.
Before any quote, not after, come three queries: the fuel that went in, the amount, and if it's run. That is why. The replies turn a range into a straight figure.
About Town Centre, briefly
Town Centre is a suburban area located on the riverside in Midlothian, with a mix of flat housing and local amenities. Town Centre sits at an elevation of 189 metres, near the communities of Broomhill, Valleyfield, and Eskhill. Town Centre is situated approximately 8.9 miles from Edinburgh, making it a commuter base for the city. Town Centre has a population of around 2885 people, with the majority residing in flat accommodation.
Fuel drain cover in Town Centre and across Midlothian
Petrol in diesel calls around Town Centre — part of the EH postcode area — go to vans that likewise cover the places about it, Broomhill, Valleyfield and Eskhill included. The car does not need to move to us: we drain on a forecourt, in a supermarket car park, in a lay-by or on your own driveway.
In Town Centre and still at the petrol pump?
The best spot there is, then — that's where you are. Keep it off. Phone.