Should You Worry? Petrol in a Diesel Car in Badgworth
Less than you likely are, if it has not been started. Petrol resting in a diesel tank does nothing to your engine till something pulls it through the fuel system — the ignition priming the pump, the starter, or the drive on its own. So the honest answer to the first question everyone in Badgworth asks, "have I ruined it?", is normally no. Petrol in Diesel is who to ring, with the motor left off, and so it remains that way. The remainder of this page sets out what petrol really does to a diesel, how to judge how far it has got, and how to make sure it doesn't happen to you again.
Petrol in a diesel: what does it do to the motor?
Diesel does two tasks on its way through a motor. It lubricates first, and only then does it burn. What keeps the surfaces inside your high-pressure pump and the injectors from grinding against one another is your diesel flowing through them — they're built to very fine clearances.
Badly at the first, not at all at the second: that is petrol. A pump working on a petrol mix is wearing itself out, because petrol is thinner than diesel and strips out the protection the fuel system depends on. Petrol is also made to resist igniting under compression — the opposite of what a diesel wants from its fuel — and that is where any rattling comes.
Together, those leave the shape of the trouble clear. The harm is done by movement, not by contact. Petrol in a tank is a fuel issue. Once the pump has been labouring on that petrol, a mechanical problem has begun: anything shed by a pump that's wearing down travels downstream to the injectors with the fuel.
How bad is petrol in a diesel? Four scenarios our technicians see around Badgworth
Fuelled up, not once started. The best case there is. The petrol is inside that tank and just the tank, and the task is a drain and a flush where the vehicle sits. 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.
Started for a second, or just the ignition on. The system has been bled, so petrol has left that tank and got to your filter and the fuel lines. Still usually simple: drain, flush, and your filter sorted.
The pump has worked a couple of miles on weakened fuel — that's what driving it does. The work is the tank, the lines, your filter and clean fuel through the whole system, and how hard the car was driven matters as much as how far. On the school run to Weare Academy First School, the miles is short. Very different again: a trip to Wells, under 15 miles away, or some miles on the M5, under 3 miles from Badgworth, where the engine kept labouring hard.
Driven till it protested. Knocking, a ragged idle, smoke, a throttle that has gone soft. That is the engine telling you its fuel has stopped acting like diesel. Pull up on the spot — on the verge on Church Lane, at the kerb, down a side road — and do not move it. The drain and flush-through still come first, and they deal with it: if a car is stopped soon, permanent damage is very uncommon.
Badgworth people and that petrol in a diesel myths they hear
Myth: "Fill it the rest of the way with diesel and it will be fine." It will not. Nothing is removed by topping up — you're left with a bigger tank, still the same mix. A diesel fuel system doesn't accept petrol by percentage in the way that advice presumes.
If anything, the opposite is true. Myth: "A newer diesel can cope with a bit of petrol." Finer parts and higher pressure are how a newer diesel runs its fuel, and that makes the protection count more, not less.
"It starts, it drives, and so no harm done" — the myth that trips up more motorists than any other. The motorist of a petrol motor fed diesel normally stops, since it will not run, and the harm stops there. A diesel fed petrol normally starts, ticks over and drives away as though nothing has happened, whilst the pump grinds. Fine and running are not the same at all.
"A drop of two-stroke oil and drive it home" — a myth, borrowed from a fix from years ago, for a distinct issue. The petrol is still in the tank after that, and what it has diluted isn't put back.
"Drain it yourself and you are sorted" — a myth, since after it has been running some petrol lies in the filter and lines, ready to go straight back through the pump at the next start. It's also really hazardous to drain petrol into a can by the kerbside.
How it happens: petrol in a diesel
Carelessness is rarely the cause, and nobody means to do it. The forecourt makes it simple: the petrol nozzle is the slimmer of the two, and it slides into a diesel filler with almost no resistance, while a diesel nozzle generally won't go into a petrol car at all. So the slip runs one way.
The moment routine stops matching your car is the moment it occurs. A vehicle that's 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 laid out differently. Fuelling up in a rush on the way to Highbridge & Burnham, with a train to catch. Years of petrol vehicles behind you, a diesel Volkswagen Golf in front of you at the forecourt for its first tank — that's when. Throw in rain, a phone call or a back seat full of kids, and the hand does what it has always done.
How to avoid petrol in a diesel on your next fill-up in Badgworth
- Read the pump, not the colour. In the UK unleaded handles are usually green and diesel black, but not on each forecourt. The label is what counts.
- Check your filler flap. Plenty of motors state the fuel inside the flap or on the cap. Look at it on your first fill in any motor you don't know.
- Good intentions do less than a sticker or a fob in a vivid colour on your diesel's key when a home has one of each. So mark it.
- "Diesel", aloud, before you lift the nozzle — each time a new or hired car needs its first tank. It seems silly. It works.
- Tuck the phone away. This is an easy mistake to make while you're thinking about something else.
- Some diesels come with a filler built to reject a petrol nozzle, and devices you can add exist for vehicles without one. Such an inhibitor helps up to a point — as a safety net, not a reason to stop reading the pump.
- The moment you notice, stop: less petrol inside that tank means a weaker mixture. What to do next does not change, though — still do not fire it up.
Put petrol in a diesel around Badgworth already?
Short and simple, then, is the order of things. Do not turn your ignition on, and do not fire it up. If you're still on the forecourt — BP Weare or anywhere else — ask the staff to help you push it clear of the pump. Phone 0333 366 0103 next, with three facts — the fuel, the approximate amount, and if it has run.
AdBlue, not petrol? Then say so. Corrosion and deposits, not lost lubrication, make it a separate issue — Badgworth has a page all for it.
Why one petrol in a diesel job in Badgworth costs more than another
The four situations above are four separate jobs, so no single quote for this would be honest. What shifts the cost is mostly which of them you are in. The proportion counts next, meaning how much of that tank is petrol, and then the location of the car and whether reaching it is safe for our van.
What went in, how much, and if it's run — three queries our technicians ask before pricing, not after, for exactly that reason. Those replies are what change a range into one firm number.
About Badgworth
Badgworth is a small village in inland Somerset, situated near the villages of Biddisham and Stone Allerton. Badgworth lies close to the Somerset Levels, with its elevation of around 9 metres above sea level. Badgworth is characterised by its predominantly detached housing stock, reflecting its rural setting. Badgworth is located approximately 10.5 miles from the city of Wells, and around 119 miles from London.
Badgworth and Somerset: where our fuel drain cover reaches
Badgworth sits in the BS postcode area, and the teams that answer petrol in diesel jobs there work the spots around it as well — Biddisham, Stone Allerton and Tarnock among them. Our engineers drain wherever the car is — your own driveway, a lay-by, a supermarket car park, a forecourt — so it never needs to come to us.
Badgworth: still at the petrol pump?
The best place there is, then — that is where you are. Ring, and keep it turned off.