How Worried Should You Be? Petrol in a Diesel Car in Dorchester
Less than you likely are, provided it has not been started. "Have I wrecked it?" is the first question anyone around Dorchester asks, and the honest answer is normally no, since petrol left in a diesel tank hurts nothing until it's drawn through your fuel system — by ignition priming, by the starter, or by driving. Keep it that way: leave your motor off then call Petrol in Diesel. What petrol actually does to a diesel, how to judge how far it has gone, and how to keep it from happening a second time: that is the rest of this page.
What petrol in a diesel does to your engine
Passing through an engine, diesel is doing two jobs at the same time. It lubricates to begin with, and only then does it burn. Made to extremely fine tolerances, the fuel injectors and the pump rely on your diesel flowing through them to stop their surfaces wearing against one another.
Poorly at the first, not at all at the second: that's petrol. A pump running on a petrol mix is wearing itself out, since petrol is thinner than diesel and takes away the lubrication your 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's where any rattling comes.
Taken together, they show what shape the issue takes. It's circulation that does the damage, not contact. A tank with petrol in it is a fuel fault. 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 the fuel to the injectors beyond it.
How bad is petrol in a diesel? Four scenarios our technicians see around Dorchester
The best case there is: filled up, never started. That petrol is inside your tank and only that tank, and the job is a drain and a flush where the vehicle sits. This is the one situation that can only truly take place at a forecourt, because anywhere else the car has been driven to get there.
Ignition on, or started for a second. Once primed, the system has drawn petrol out of the tank as far as the filter and your lines. That's normally still an easy task — a drain, a flush, and your filter dealt with.
A few miles driven, and your pump has spent each of them labouring on weakened fuel. The work is your tank, your lines, the fuel filter and fresh fuel through the entire circuit, and how hard the car was driven counts as much as how far. Short trips, such as the school run to St Mary's Catholic First School, Dorchester, are one thing. A run as far as Wells, under 50 miles away, is a very different task. So is any distance on the M5, under 50 miles from Dorchester, where your engine has been running hard the whole time.
Rattling, a ragged idle, smoke, a throttle gone soft: driven till it complained. The fuel isn't acting like diesel any more, and the motor is saying so. Pull up on the spot — on the verge on High West Street, at the kerb, down a side road — and do not move it again. The drain and flush-through still come first, and they sort it out: if a car is stopped soon, lasting damage is very unusual.
What Dorchester motorists get told about petrol in a diesel — and the myths in it
Myth: "Fill it the rest of the way with diesel and it'll be fine." It will not. Nothing is removed by topping up — you are left with a bigger tank, still the same mixture. The assumption behind that advice — that diesel fuel systems accept petrol by percentage — is wrong.
If anything, the reverse is true. Myth: "A newer diesel can cope with a bit of petrol." Smaller parts and higher pressure are how a newer diesel runs its fuel, and that makes the protection matter more, not less.
"It starts, it drives, and so there is no harm" — the myth that catches more motorists than any other. The motorist of a petrol motor fed diesel normally stops, since it will not run, and the damage stops there. Feed petrol to a diesel and it generally fires up, ticks over and pulls away like nothing happened — all the while its pump wears. Fine and running aren't the same at all.
Myth: a two-stroke additive lets you to drive home. It was an old fix, meant for another issue. What petrol has weakened stays diluted, and the petrol remains inside your tank regardless.
"Drain it yourself and you're 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. On top of that, petrol emptied into a can by the road is genuinely hazardous.
How it happens: petrol in a diesel
It's seldom carelessness, and no one does it on purpose. One way only, since of the nozzles: the slimmer petrol one slips inside a diesel filler with almost no resistance, while the diesel one generally will not fit a petrol vehicle. That's how the forecourt makes it simple.
The moment routine stops matching the car is the moment it occurs. Hire cars, courtesy cars, and cars that are new to you. Two cars on one drive, one petrol, one diesel. A forecourt you know, only with its pumps laid out differently. Fuelling up in a hurry en route to Dorchester West, with a train to catch. A new-to-you diesel Volkswagen Tiguan, its first fuelling, and a motorist used to petrol: exactly when it happens. With rain, a call coming in, or children to deal with, the hand simply does what it always has.
Dorchester drivers: how to avoid petrol in a diesel next time
- Not every forecourt in the UK keeps to green for unleaded and black for diesel, though most generally do. Read the pump's label; the colour is just a clue.
- The first fill in an unfamiliar motor is the time to check the filler flap — on it, or on the cap, plenty of vehicles state the fuel they take.
- One of each in the household? Mark the key to the diesel — a coloured fob, a sticker — since intending to remember is not enough.
- It sounds daft and it does the trick: on the first fill in a new or hired car, say "diesel" aloud before you take the nozzle off the petrol pump.
- Thinking about something else is when this becomes an easy mistake to make, and so tuck the phone away and keep your mind on the petrol pump.
- Up to a point, a misfuel inhibitor helps: some diesels have a filler designed to refuse a petrol nozzle, and add-on devices exist for the rest. Count it as a safety net, then keep reading the petrol pump.
- Less petrol means a weaker mix, and so stop as soon as you notice — while remembering that the next stage is unchanged. It's still not to crank it.
Already put petrol in a diesel around Dorchester?
The order of things is brief, then. Starting it is out, and so is switching on your ignition. Yet on the forecourt, at BP or anywhere else? Ask the attendants to help you roll the car clear of the pump. Then ring 0333 366 0103 and tell us what went in, about how much, and whether it's run.
Corrosion and deposits form the trouble with AdBlue, where petrol brings lost protection. So if it was AdBlue, say so — and read its own Dorchester page.
Dorchester petrol in a diesel tasks: why one costs more than another
The four situations above are four different jobs, so no single quote for this would be fair. Which of them you are in is mostly what moves your cost. Where your car is counts too, and whether a technician can safely get to it, after the proportion of petrol to what the tank holds.
That's why our engineers ask three queries before quoting rather than after: what was put in, how much, and if it's run. Given the answers, you get a straight figure instead of a range.
About Dorchester itself
Dorchester is a town situated on the River Frome in south Dorset, with a mix of old and new buildings, including many terraced houses. Dorchester sits at an elevation of around 73 metres, near the villages of Frome Whitfield and Cokers Frome. Dorchester is located approximately 35 miles from Wells and 114 miles from London, making it a significant settlement in the area. Dorchester has a population of around 16210 people, living in a variety of housing types, predominantly terraced homes.
Dorchester and Dorset: where our fuel drain cover reaches
Petrol in diesel jobs around Dorchester — part of the DT postcode area — go to vans that also cover the spots about it, Frome Whitfield, Cokers Frome and Burton included. We drain where the car is — your own driveway, a lay-by, a supermarket car park, a forecourt — so it does not have to come to us.
At the petrol pump around Dorchester, right now?
Then you're in the best place there can be. Leave it switched off, and ring.