How Worried Should You Be? Petrol in a Diesel Car in Fremington
If it has not been started, worry far less than you probably are. "Have I wrecked it?" is the first question everyone around Fremington asks, and the truthful answer is generally no, because petrol resting in a diesel tank harms nothing until it's dragged through your fuel system — by ignition priming, by the starter, or by driving. Keep it like that: leave your engine off and ring Petrol in Diesel. Below, this page sets out what petrol actually does inside a diesel, how far it might have got, and how to stop it happening to you again.
What petrol in a diesel does to the engine
On its way through a motor, diesel does two tasks. Before it ignites, it lubricates — then it ignites. Very fine tolerances are built into the fuel injectors and the high-pressure fuel pump, and only your diesel running through stops their surfaces grinding together.
The second task petrol doesn't do at all, and the first it does poorly. Being less viscous than diesel, petrol strips out the protection a fuel system needs, so a pump on the blend wearing itself. It is also made to resist igniting under compression — the opposite of what a diesel needs — which is where you hear the rattling.
Put those together and the shape of the trouble is clear. Not contact but circulation is what does the harm. Where the petrol is only in that tank, it is a problem of fuel, nothing more. The start of a mechanical problem is a pump that has been labouring on that petrol — and whatever a worn pump sheds moves on with your fuel to the injectors downstream.
Four scenarios our engineers see around Fremington: how bad is petrol in a diesel?
The best case there can be: filled up, not once started. Only your tank has petrol in it, and so the job is emptying that tank and flushing the fuel system where the vehicle stands. This scenario can only truly happen at a forecourt: anywhere else, the car got there by being driven.
Ignition on, or started for a second. With your system primed, the fuel lines and filter now contain petrol that came from that tank. Still generally straightforward: drain, flush, and your filter dealt with.
A couple of miles driven, and the pump has spent each of them running on diluted fuel. Tank, lines, filter, then fresh fuel run through the entire system: that's this work, and the way the vehicle was driven matters as much as the distance. The school run to Fremington Primary School is one thing. Getting as far as Exeter, under 50 miles away, makes a very different job — as does any mileage on the M5, under 50 miles from Fremington, with your engine labouring hard all the way.
Driven until it complained. Knocking, a lumpy idle, smoke, a throttle that has gone soft. What you are hearing is the engine signalling fuel that no longer runs like diesel. Stop wherever you are — the verge on Higher Road, a lay-by, a side street — then leave the vehicle where it is. What goes first is still the fuel drain and flush, and that deals with it, with long-term damage very rare when a car is stopped soon.
Myths Fremington people hear about petrol in a diesel
It will not be fine. The myth: "Fill it the rest of the way with diesel and it will be." Nothing comes out when you top up — the tank simply holds more of the same blend. A diesel fuel system doesn't tolerate petrol by percentage in the way that advice assumes.
Myth: a modern diesel copes with a bit of petrol. Rather, the opposite. Smaller parts and higher pressure are how a newer diesel runs its fuel, and that makes the protection matter more, not less.
This is the one that fools people. Myth: "If it starts and drives, there is no damage done." The driver of a petrol motor fed diesel normally stops, since it will not run, and the damage stops with them. Nothing looks to have happened when a diesel fed petrol fires up, ticks over and drives away, as it usually will; meanwhile your pump grinds. A running engine doesn't mean fine.
Myth: "Add some two-stroke oil and drive the vehicle home." It's an outdated fix for a distinct fault. It doesn't put back what petrol has diluted, and that petrol is still in that tank later.
The next start draws petrol back round the pump out of the lines and the filter, where some of that ends up after the engine has run. That is why a DIY tank drain doesn't sort it — a myth. Also, a can of petrol drained by the roadside is genuinely risky.
Petrol in a diesel: how does it take place?
A careless moment is rarely the cause, and nobody means to do it. One way only, because of the nozzles: the narrower petrol one slips inside a diesel filler with almost no resistance, while the diesel one mostly will not fit a petrol car. That's how the forecourt makes it easy.
When habit and the vehicle stop matching, it happens. Hire cars, courtesy cars, and motors that are new to you. Two vehicles on one drive, one petrol, one diesel. A well-known forecourt with the pumps in a different order. A train to catch, and a rushed fill en route to Barnstaple. Precisely the moment it takes place: after years of driving petrol, someone fills a diesel Volkswagen Golf for the first time. Throw in a back seat full of children, a phone call or rain, and the hand wins.
Next time you fill up in Fremington: avoiding petrol in a diesel
- Green for unleaded and black for diesel is normal in the UK — yet not on every forecourt. Trust the label on the petrol pump, not the colour.
- The first fill in a new motor is the time to check the filler flap — inside it, or on the cap, plenty of cars state which fuel they take.
- Good intentions do less than a sticker or a fob in a vivid colour on your diesel's key when a household has one of each. So label it.
- Say it before you lift it. On your first fill in a new or hired car, say "diesel" out loud before you take the nozzle off the pump. It sounds daft and it works.
- Mistakes like this are easy to make while your mind is on something else, so the phone goes away.
- Some diesels have a filler designed to block a petrol nozzle, and devices you can add exist for motors 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 mixture. It does not change what to do next, which is still not to crank it.
Petrol already in a diesel around Fremington? Start here
In that case, there's just a short order of things. Leave it unstarted, with your ignition off as well. The attendants at the forecourt — whether at Murco itself or wherever you filled up — will normally help roll it clear of the pump if you ask. Then call 0333 366 0103 and tell us what was put in, about how much, and whether it has run.
Say so if it was AdBlue instead of petrol: it's a separate issue, with its own page for Fremington, because AdBlue brings corrosion and deposits rather than lost protection.
Why one petrol in a diesel job in Fremington costs more than another
The four scenarios above are four separate tasks, so no single quote for this would be honest. What shifts your cost is mostly which of them you are in. The proportion matters next, meaning how much of that tank is petrol, and then the location of your car and whether getting to it is safe for a technician.
Ahead of any quote, not after, we ask three queries: your fuel that went in, its volume, and if it's run. That is why. A range turns into a straight figure when those answers are in.
About Fremington and where it is
Fremington is a village in Devon, situated on the riverside at a low elevation of around 16 metres. Fremington lies near several smaller settlements, including Muddlebridge, Combrew, and Lower Yelland, and is approximately 35 miles from the city of Exeter. Fremington has a population of around 2234 people, predominantly living in detached houses. Fremington is located in the South West region of England, about 175 miles from London.
Fuel drain cover across Devon, Fremington included
Fremington sits in the EX postcode area, and the vans that answer petrol in diesel calls there work the places around it as well — Muddlebridge, Combrew and Lower Yelland among them. No need to bring the car to us. Forecourts, supermarket car parks, lay-bys and your own drive are all places where we work.
At the pump around Fremington, still?
Then you are in the best spot there is. Phone, and leave it switched off.