Camber: Petrol in a Diesel Car? How Worried to Be
Less than you probably are, if it has not been started. Until the ignition primes your pump, your starter cranks, or the vehicle is driven, petrol in a diesel tank simply sits there and does nothing. Which makes the honest reply to the first Camber query — "have I ruined it?" — normally no. Leave the motor off then ring Petrol in Diesel — that is how you keep it that way. The rest of this page explains what petrol really does to a diesel, how to tell how far it has got, and how to make sure it doesn't happen to you a second time.
The engine and petrol in a diesel: what happens
Diesel does two jobs on its way through a motor. Before it combusts, it lubricates — and then it ignites. What keeps the surfaces inside your high-pressure pump and the fuel injectors from grinding against each other is the diesel flowing through them — they are built to extremely fine clearances.
Petrol does the first task badly and the second not at all. A pump running on a petrol blend is wearing itself out, since petrol is runnier than diesel and takes away the protection the fuel system relies on. Petrol is also designed to resist igniting under compression — the opposite of what a diesel wants from its fuel — and that's where any knocking starts.
The shape of the problem is clear once you put those together. Not contact but movement is what causes the harm. Petrol in the tank is a fuel problem. After the pump has been running on that petrol, a mechanical fault has begun: whatever is shed by a pump that's grinding is carried onward to the injectors with your fuel.
Camber, petrol in a diesel: four cases, from mild to significant
Filled but not once started — as good as it gets. Being on a forecourt is what makes this the case: elsewhere, the vehicle has been driven there to begin with. With the petrol held inside the tank alone, it is cleared and purged right where it stands, and nothing more is needed.
A brief spell of running, or merely your ignition on. Petrol has left your tank and reached the fuel filter and the fuel lines, because the fuel system has been bled. Usually nothing more than clearing, flushing and seeing to your filter, and so still easy.
Those few miles on the road meant your pump running on fuel thinned by petrol the whole way. Tank, lines, filter, then clean fuel run through the entire system: that's this work, and the way the vehicle was driven counts as much as the distance. On the school run to Rye Community Primary School, the distance is short. Driving as far as Canterbury, under 50 miles away, makes a very different job — as does any miles on the M20, under 15 miles from Camber, with your engine running hard all the way.
Rattling, a lumpy idle, smoke, a throttle gone soft: driven till it complained. What you are hearing is the motor reporting fuel that no longer runs like diesel. Stop on the spot — on the verge on First Avenue, at the kerb, down a side road — and don't move it again. A vehicle pulled over quickly very rarely has lasting damage, as the drain and the flush, which still come first, sort it out.
Camber motorists and the petrol in a diesel stories they hear
Myth: "Fill it the rest of the way with diesel and it'll 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 doesn't tolerate petrol by percentage in the way that advice assumes.
If anything, the opposite is true. Myth: "A current diesel can cope with a bit of petrol." At higher pressure, through more precise components: that's how a modern diesel moves its fuel, so the lubrication counts more, not less.
Myth: "If it starts and drives, there's no harm done." This is the one that catches motorists. Diesel in a petrol motor normally means a motor that will not run: the motorist stops, and so does the damage. Whilst the pump wears, a diesel fed petrol usually starts, ticks over and drives away as though nothing has happened. Running doesn't mean fine.
"A drop of two-stroke oil and drive it home" — a myth, taken from a fix from years ago, for a separate fault. That petrol is still inside the tank afterwards, and what it has diluted is not put back.
The next start sends petrol back round your pump out of the fuel lines and the filter, where some of it ends up after your engine has been run. That's why draining the tank yourself doesn't leave you sorted — a myth. It is also genuinely hazardous to drain petrol into a can at the kerbside.
Petrol in a diesel: how does it happen?
It's seldom carelessness, and no one does it on purpose. The petrol nozzle is the smaller of the two and slides into a diesel filler with almost no resistance; a diesel nozzle generally won't go into a petrol vehicle at all. The forecourt makes it easy, and the error runs one way.
Habit and the vehicle falling out of step is when it occurs. Hire cars, courtesy cars, and vehicles that are new to you. A household with one petrol and one diesel on the driveway. A forecourt you know, only with its pumps arranged differently. Fuelling up in a rush on the way to Rye, with a train to catch. Precisely the moment it takes place: after years of driving petrol, a driver fills a diesel Renault Megane for the first time. Throw in rain, a phone call or a back seat full of children, and your hand repeats what it has always done.
Avoiding petrol in a diesel next time you fill up around Camber
- Read 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 your filler flap. Plenty of cars state the fuel inside the flap or on the cap. Look at it on your first fill in a car you do not know.
- Good intentions count for less than a sticker or a fob in a vivid colour on the diesel's key if a home has one of each. So label it.
- "Diesel", out loud, before you pick up the nozzle — every time a new or hired car gets its first tank. It sounds daft. It does the trick.
- Thinking about something else is when this becomes an easy mistake to make, and so tuck the phone away then keep your mind on the pump.
- A misfuel inhibitor helps, up to a point. Some diesels come with a filler designed to block a petrol nozzle, and add-on devices exist for cars without one. They are a safety net, not a reason to stop reading the petrol pump.
- Less petrol makes a thinner blend, so stop as soon as you realise — while remembering that the next stage is unchanged. It's still not to crank it.
Petrol already in a diesel in Camber? Start here
The order of things is brief, then. Starting it is out, and so is switching on your ignition. If you are still at the forecourt — Murco or anywhere else — ask the staff to help you push the vehicle clear of the petrol pump. What got in, roughly how much, and whether it has run: tell us that when you ring 0333 366 0103.
Corrosion and deposits form the issue with AdBlue, whereas petrol means lost protection. So if it was AdBlue, say so — and read its own Camber page.
Camber petrol in a diesel jobs: why one costs more than another
The four situations above are four separate tasks, so no single price for this would be honest. Mostly, your cost moves with which situation you are in. Beyond that it is the proportion — how much petrol got in against how much the tank takes — and after that where your car is and whether our van can reach it safely.
That's why we ask three queries before costing instead of after: what went in, how much, and whether it's run. With the replies, there is a straight figure rather than a range.
About Camber itself
Camber is a small coastal village in East Sussex, situated near the Kent border and close to the towns of Rye and Winchelsea. Camber sits on the edge of Romney Marsh, at a low elevation of around 2 metres, and is surrounded by scenic beaches and nature reserves. Camber is characterised by its detached housing and quiet, rural atmosphere, with nearby places including Jurys Gap and Rye Harbour. Camber is also within commuting distance of larger cities like Canterbury and London.
Fuel drain cover across East Sussex, Camber included
The teams answering petrol in diesel calls around Camber, in the TN postcode area, equally work the places near it, Jurys Gap, Rye Harbour and East Guldeford included. The vehicle does not need to come to us: our engineers drain at a forecourt, in a supermarket car park, in a lay-by or on your own drive.
Still at the pump in Camber?
Then, you could not be in a better place. Switched off it stays; then ring.