Petrol in a Diesel Car in Churchhill: How Worried Should You Be?
Provided it has not been started, worry less than you likely are. Everyone in Churchhill starts with "have I ruined it?", and the fair answer is normally no: petrol resting inside that tank of a diesel stays harmless until priming, cranking or driving draws it into your fuel system. Leave the motor off then call Petrol in Diesel — that is how you keep it like that. 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 doesn't happen to you a second time.
Inside the engine: what petrol in a diesel really does
Diesel has two jobs on its way through an engine. Before it combusts, it lubricates — and then it ignites. Very fine clearances are built into the fuel injectors and your high-pressure pump, and just your diesel flowing through stops those surfaces grinding together.
Petrol does the first task badly and the second not at all. It's thinner than diesel and strips away the protection the fuel system depends on, and so a pump running on a petrol blend 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 is where the rattling comes from.
Taken together, they make clear what shape the issue has. Contact does not do the damage — circulation does. Where that petrol is only inside your tank, it's a fault of fuel, nothing more. The beginning of a mechanical problem is a pump that has been running on that petrol — and whatever a worn pump sheds moves on with your fuel to the fuel injectors downstream.
How bad is petrol in a diesel? Four scenarios we see in Churchhill
Fuelled, and never started: nothing beats it. On a forecourt, and genuinely only there, the petrol is still limited to your tank — because anywhere else the car was driven to reach it. The task is emptying and purging on the spot.
Ignition on, or started for a moment. Once primed, the system has drawn petrol out of your tank up to the fuel filter and the fuel lines. Drain, flush, deal with the filter: still normally easy.
The pump now worked a couple of miles on thinned fuel — that's what driving it does. Distance is only half of it; how hard it was driven matters just as much. Either way this work includes your tank, the lines, the filter and fresh fuel through the whole circuit. Driving the kids to the local primary school is one sort of trip. Very different a second time: a trip to Edinburgh, under 3 miles away, or any distance on the M8, under 5 miles from Churchhill, where the motor kept running hard.
It complained, and only then stopped: smoke, rattling, a throttle gone soft, an idle gone lumpy. What you are hearing is the engine signalling fuel that no longer acts like diesel. Stop wherever you are — the verge on Colinton Road, a lay-by, a side street — then leave the car where it is. What goes first is still the drain and flush, and that sorts it out, with lasting damage very uncommon if a vehicle is stopped soon.
Myths Churchhill motorists hear about petrol in a diesel
"Top it up the rest of the way with diesel and it will be fine" — a myth. It won't. A fuller tank of the same mix is all it gives, because topping up takes out nothing. The idea behind that guidance — that diesel fuel systems tolerate petrol by percentage — is wrong.
"Modern diesels can handle a little petrol" — a myth, and closer to the reverse. More precise parts and higher pressure are how a modern diesel runs its fuel, and that makes the lubrication matter more, not less.
The myth that catches drivers out: if it starts and drives, it must be unharmed. The driver of a petrol motor fed diesel normally stops, because it will not run, and the harm stops there. A diesel fed petrol usually starts, idles and drives away as though nothing has happened, whilst your pump grinds. 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. None of what petrol weakened is put back by it — and afterwards, that tank still holds the petrol.
"Drain it yourself and you are sorted" — a myth, since after it's been running some petrol sits in the filter and lines, ready to go right back through the pump at the next start. And, a can of petrol filled by the kerbside is truly risky.
How it happens: petrol in a diesel
It is seldom carelessness, and no one does it on purpose. The petrol nozzle is the smaller of the two and slips into a diesel filler with almost no resistance; a diesel nozzle mostly will not go into a petrol motor at all. The forecourt makes it easy, and the error runs one way.
When habit and the vehicle stop matching, it happens. Hire cars, courtesy cars, and vehicles that are new to you. A household with one petrol and one diesel on the drive. A well-known forecourt with the pumps in a different order. A train to catch, and a hurried fill en route to Haymarket. Years of petrol motors behind you, a diesel Renault Megane in front of you at the forecourt for its first tank — that is when. Throw in a back seat full of children, a phone call or rain, and the hand takes over.
Churchhill drivers: how to prevent petrol in a diesel next time
- The label is what matters, and so check the pump instead of the colour: in the UK unleaded handles are usually green and diesel black, but not on every forecourt.
- In a car you do not know, look inside the flap over the filler or at the cap before the first fill: many motors print the fuel there.
- A coloured fob or a sticker on the diesel's key does more than any amount of meaning to remember, for a home with one of each.
- It seems silly and it works: on the first fill in a new or hired car, say "diesel" out loud before you lift the nozzle off the petrol pump.
- Mistakes like this are easy to make whilst your mind is on something else, so the phone goes away.
- Some diesels have a filler built to reject a petrol nozzle, and devices you can add are available for vehicles without one. Such an inhibitor helps up to a point — as a backstop, not a reason to stop checking the petrol pump.
- Stop the moment you notice. Less petrol inside that tank means a thinner blend. It does not change what to do next, which is still not to fire it up.
Already put petrol in a diesel around Churchhill?
The order of things is brief, then. Do not turn your ignition on, and do not fire it up. If you're still on the forecourt — JET or anywhere else — ask the attendants to help you roll the vehicle away from the pump. Then ring 0333 366 0103 and tell us what went in, roughly how much, and if it has run.
Corrosion and deposits form the trouble with AdBlue, whereas petrol means lost lubrication. So if it was AdBlue, say so — and see its own Churchhill page.
Why one petrol in a diesel task in Churchhill costs more than another
The four situations above are four different jobs, so no single quote for this would be honest. What shifts your cost is mostly which of them you're in. Beyond that it is the proportion — how much petrol went in against how much the tank holds — and after that where the vehicle is and whether a van can get to it safely.
That's why we ask three queries before pricing instead of after: what got in, how much, and if it has run. The answers change a range into a straight figure.
About Churchhill, briefly
Churchhill is a suburban area in the City of Edinburgh, situated approximately 1.6 miles from Edinburgh city centre. Churchhill occupies a coastal setting with an elevation of around 101 metres, looking out towards the Firth of Forth. Churchhill is characterised by its predominantly flat-type housing and is located near other Edinburgh suburbs such as Bruntsfield and Merchiston.
Fuel drain cover in Churchhill and across City of Edinburgh
Bruntsfield, Merchiston and Fountainbridge are among the locations near Churchhill that the same vans work, answering petrol in diesel calls across Churchhill's EH postcode area. Our technicians drain where your vehicle is — your own drive, a lay-by, a supermarket car park, a forecourt — so it never needs to come to us.
In Churchhill and still at the petrol pump?
Then you're in the best place there is. Call, and leave it turned off.