How Worried Should You Be? Petrol in a Diesel Car in Preston
Not started? Then less worried than you probably feel. Petrol resting in a diesel tank does nothing to your engine till something draws it through your fuel system — the ignition priming your pump, the starter, or driving on its own. So the truthful answer to the first question everyone in Preston asks, "have I wrecked it?", is generally no. Keep it like that: leave your motor off and call Petrol in Diesel. The rest of this page covers 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.
What petrol in a diesel does to the motor
Two tasks fall to diesel on its journey through a motor. Lubricating comes before burning; it does both. What stops the surfaces inside the high-pressure fuel pump and your injectors from wearing against each other is the 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 lubrication a fuel system needs, so a pump running on the blend wearing itself. It is also made to resist igniting under compression — the reverse of what a diesel needs — which is where you hear the clattering.
Put these together and the shape of the problem is clear. The damage is done by movement, not by contact. Petrol in a tank is a fuel problem. The start of a mechanical one is a pump that has been labouring on that petrol — and whatever a worn pump sheds moves on with the fuel to your injectors beyond it.
Four situations our engineers see in Preston: how serious is petrol in a diesel?
Filled up, not once started. The best case there can be. The petrol is in that tank and just the tank, and the task is a drain and a flush where the car stands. This is the one scenario that can only truly take place at a forecourt, as anywhere else the vehicle has been driven to get there.
The ignition switched on, or a short start. The system has been primed, and so petrol has left your tank and got to your filter and your lines. That is generally still a straightforward task — a drain, a flush, and the fuel filter seen to.
Driven a few miles. Now the pump has spent those miles running on diluted fuel. Tank, lines, filter, then clean fuel run through the entire circuit: that is the work, and the way the car was driven matters as much as the miles. On the school run to Stanford Infant School, the mileage is small. Driving as far as Brighton and Hove, under 3 miles away, makes a very different job — as does any mileage on the M23, under 25 miles from Preston, with the engine working hard the whole time.
Knocking, a ragged idle, smoke, a throttle gone soft: driven until it complained. That's your motor telling you its fuel no longer is behaving like diesel. Pull up wherever you are — the verge on Stanford Road, a lay-by, a side street — and leave the vehicle where it is. What comes first is still the drain and flush, and that deals with it, with long-term damage very uncommon when a car is pulled over quickly.
Preston people and the petrol in a diesel stories they hear
It will not be fine. The myth: "Fill it the rest of the way with diesel and it'll be." Nothing is removed by topping up — you are left with a fuller tank, still the same mixture. The idea behind the advice — that diesel fuel systems tolerate petrol by percentage — is wrong.
If anything, the reverse holds. Myth: "A current diesel can cope with a bit of petrol." Smaller parts and higher pressure are how a current diesel runs its fuel, and that makes the lubrication matter more, not less.
This is the one that fools drivers. Myth: "If it starts and drives, there is no damage done." Any petrol motor fed diesel usually will not run, so the motorist stops and the harm stops with them. While your pump grinds, a diesel fed petrol usually starts, idles and drives away as if nothing has happened. Running doesn't mean fine.
"A drop of two-stroke oil and drive it home" — a myth, borrowed from a fix from years ago, for a distinct issue. It does not put back what petrol has weakened, and the petrol is still in your tank later on.
Myth: "Drain that tank yourself and you are sorted." After your engine has been run, some of the petrol is no longer in the tank: it is in your filter and your lines, and it goes right back through your pump on the next start. Also, a can of petrol drained by the kerbside is genuinely dangerous.
Petrol in a diesel: how does it occur?
On purpose? Never. Through carelessness? Rarely, if ever. 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, whilst a diesel nozzle generally will not go into a petrol car at all. So the error runs one way.
When habit and the vehicle stop matching, it takes place. A vehicle that is new to you — hired, on loan as a courtesy car, or brand new. One petrol and one diesel on the driveway of the same household. A forecourt you know, only with its pumps arranged differently. A train to catch, and a hurried fill en route to London Road (Brighton). Precisely the moment it occurs: after years of driving petrol, a driver fills a diesel Volkswagen Golf for the first time. The hand repeats what it has always done once you add rain, a phone call or a back seat full of children.
Preston people: how to prevent petrol in a diesel next time
- A green handle for unleaded and black for diesel is normal in the UK — but not on every forecourt. Go by the label on the petrol pump, not the colour.
- In a motor you don't know, look inside the flap over the filler or at the cap before your first fill: plenty of cars state the fuel there.
- Label your key. In a household with one of each, a coloured fob or a sticker on your diesel's key does more than any amount of intending to remember.
- "Diesel", aloud, before you lift the nozzle — each time a new or hired car gets its first tank. It seems daft. It does the trick.
- Tuck your phone away. This is an easy mistake to make whilst you're thinking about something else.
- A misfuel inhibitor helps, up to a point. Some diesels come with a filler built to block a petrol nozzle, and add-on devices are available for motors without one. They are a safety net, not a reason to stop checking the petrol pump.
- Stop the moment you realise. Less petrol inside the tank makes a thinner mix. It does not change what to do next, which is still not to crank it.
Put petrol in a diesel around Preston already?
The order of things is brief, then. Don't fire it up, and do not turn the ignition on. Still at the forecourt, at Esso or anywhere else? Ask the attendants to help you roll it away from the petrol pump. Ring 0333 366 0103 next, with three answers — your fuel, the rough quantity, and if it has run.
Say so if it was AdBlue instead of petrol: it is a separate problem, with its own page for Preston, because AdBlue brings corrosion and deposits instead of lost lubrication.
One petrol in a diesel task around Preston costs more than another. Why?
There is no fair single price for this, since the four scenarios above are four separate tasks. Which of them you are in is mostly what shifts your cost. Where the vehicle is matters too, and whether a technician can safely get to it, after the proportion of petrol to what your tank takes.
What went in, how much, and if it has run — three queries we ask before quoting, not after, for precisely that reason. Those answers change a range into a straight figure.
About Preston, briefly
Preston is a suburban area in East Sussex, situated on the southeastern coast of England, approximately 46 miles from London. Preston lies close to the city of Brighton and Hove, with which it is closely associated, and is near other local areas such as Round Hill and Hollingdean. Preston is characterised by its predominantly flat housing stock, with many residential buildings in the area being flats. Preston's elevation is around 53 metres above sea level, giving it a relatively low-lying coastal position.
Preston and East Sussex: where our fuel drain cover runs
The vans answering petrol in diesel call-outs in Preston, in the BN postcode area, equally work the spots around it, Round Hill, Hollingdean and Withdean included. The car does not need to move to us: our engineers drain on a forecourt, in a supermarket car park, in a lay-by or on your own driveway.
In Preston and still at the petrol pump?
The best spot there is, then — that is where you are. Switched off it stays; then phone.