Should You Worry? Petrol in a Diesel Car in Ash Brake
Provided it has not been started, worry less than you probably are. "Have I wrecked it?" is the first thing anyone around Ash Brake asks, and the honest answer is usually no, since petrol resting in a diesel tank harms nothing till it is dragged through the system — by ignition priming, by the starter, or by being driven. Keep it like that: leave the motor off then call Petrol in Diesel. 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 doesn't happen to you a second time.
The engine and petrol in a diesel: what goes on
On its way through a motor, diesel has two tasks. Lubricating comes before burning; it does both. Very fine clearances are built into your injectors and your high-pressure pump, and just your diesel flowing through stops their surfaces grinding together.
Of these two jobs, petrol handles the first badly and the second never. A pump running on a petrol blend is wearing itself out, since petrol is thinner than diesel and strips out the protection the fuel system relies on. Petrol is also designed to resist igniting under compression — the reverse of what a diesel wants from its fuel — and that is where any rattling starts.
Put these together and the shape of the problem is plain. Contact doesn't do the harm — movement does. Petrol in the tank is a fuel problem. The start of a mechanical problem is a pump that has been working on that petrol — and whatever a worn pump sheds moves on with your fuel to your injectors beyond it.
How serious is petrol in a diesel? Four situations we see in Ash Brake
The best case there is: filled up, not once started. On a forecourt, and genuinely only there, the petrol is still confined to that tank — because everywhere else your car was driven to reach it. The task is draining and flushing on the spot.
A moment's running, or just the ignition on. With the fuel system primed, your lines and filter now hold petrol that has come from the tank. Still normally easy: drain, flush, and the filter dealt with.
Your pump now spent a couple of miles on weakened fuel — that is what driving the vehicle meant. Tank, lines, filter, then clean fuel run through the entire system: that is this work, and the way the vehicle was driven counts as much as the miles. A school run to Bridlewood Primary School is one thing. Driving as far as Oxford, under 50 miles away, makes a very different job — as does any mileage on the M4, under 5 miles from Ash Brake, with your engine labouring hard the whole time.
It protested, and only then stopped: smoke, clattering, a throttle gone soft, an idle gone lumpy. That's your motor telling you its fuel has stopped acting like diesel. Whether it's the verge on Pennine Way, a lay-by or a side street, stop there and leave it. What comes first is still the drain and flush-through, and that takes care of it, with long-term damage very rare when a car is pulled over quickly.
Petrol in a diesel stories Ash Brake drivers 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 mix. That advice assumes a diesel fuel system tolerates petrol by percentage. It doesn't.
If anything, the reverse holds. Myth: "A current diesel can cope with a bit of petrol." A modern diesel sends its fuel through more precise parts at higher pressure, which makes the lubrication matter more, not less.
This is the one that fools drivers. Myth: "If it starts and drives, there's no damage done." Diesel in a petrol motor generally means a motor that will not run: the driver stops, and so does the harm. A diesel fed petrol generally starts, idles and drives away as though nothing has happened, whilst the pump wears. Running is not the same as fine.
Myth: a two-stroke additive lets you to drive home. It was an old workaround, meant for another fault. It does not put back what petrol has weakened, and that petrol is still in your tank after that.
"Drain it yourself and you're sorted" — a myth, because after it's been running some petrol lies in the fuel filter and lines, waiting to go right back through the pump on your next start. Clearing petrol into a can at the kerbside is also really hazardous.
How it happens: petrol in a diesel
It is seldom carelessness, and nobody does it on purpose. A diesel nozzle generally will not fit a petrol car, yet the smaller petrol nozzle goes into the filler of a diesel nearly without resistance — so forecourts make this one mistake straightforward, and just in that direction.
When habit and the car stop matching, it occurs. Courtesy car, hire car, or a motor that is new. A household with one petrol and one diesel on the driveway. A well-known forecourt with the pumps in a different order. A train to catch, and a rushed fill on the way to Swindon. A new-to-you diesel Volkswagen Golf, its first fuelling, and a driver accustomed to petrol: exactly when it happens. Throw in a back seat full of children, a phone call or rain, and habit takes over.
Next time you fill up around Ash Brake: preventing petrol in a diesel
- 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.
- In a car you don't know, look inside the flap over your filler or at the cap before your first fill: plenty of vehicles state the fuel type there.
- A coloured fob or a sticker on the diesel's key achieves more than any amount of intending to remember, in a household with one of each.
- "Diesel", out loud, before you lift the nozzle — each time a new or hired car needs its first tank. It sounds daft. It works.
- Whilst you are thinking about something else, this is an easy mistake to make — so put your phone away.
- Some diesels come with a filler designed to refuse a petrol nozzle, and devices you can add are available for cars without one. Such an inhibitor helps up to a point — as a backstop, not a reason to stop reading the pump.
- Less petrol makes a weaker mix, so stop the moment you realise — while remembering that your next stage is unchanged. It is still not to fire it up.
Already put petrol in a diesel around Ash Brake?
Then, there's just a short order of things. Leave it unstarted, with your ignition switched off as well. Yet at the forecourt, at Asda or anywhere else? Ask the attendants to help you push it away from the petrol pump. Ring 0333 366 0103 next, with three facts — your fuel, the rough amount, and if it's run.
AdBlue, not petrol? Then say so. Corrosion and deposits, not lost protection, make it a separate problem — Ash Brake has a page all for it.
One petrol in a diesel job in Ash Brake costs more than another. Why?
The four scenarios above are four different tasks, so no single quote for this would be honest. Which of them you are in is mostly what shifts your cost. After that it's the share — how much petrol went in against how much the tank holds — and then where the vehicle is and whether a technician can reach it safely.
That is why our engineers ask three queries before pricing rather than after: what got in, how much, and if it's run. The answers turn a range into a straight figure.
About Ash Brake
Ash Brake is a suburban area situated on the riverside in Wiltshire, with a mix of housing types but predominantly detached homes. Ash Brake sits at an elevation of 103 metres, within a short drive of nearby places such as Abbey Meads and Blunsdon St Andrew. Ash Brake is located near the city of Oxford, which is approximately 25 miles away, and is also within commuting distance of London, around 72 miles to the east. Ash Brake has a population of around 6949 residents.
Across Wiltshire and around Ash Brake: fuel drain cover
Our vans answering petrol in diesel jobs around Ash Brake, in the SN postcode area, equally work the locations near it, Abbey Meads, Blunsdon St Andrew and St Andrews Ridge among them. No need to bring the vehicle to us. Forecourts, supermarket car parks, lay-bys and your own driveway are all spots where we work.
In Ash Brake and still at the pump?
Nothing beats it: that's where you now are. Turned off it stays; then phone.