Petrol in a Diesel Car in Little Knowle: How Worried Should You Be?
Far less than you likely are, provided it hasn't been started. Till your ignition primes the pump, the starter turns, or your vehicle is driven, petrol in a diesel tank just rests there and does nothing. Which makes the truthful reply to that first Little Knowle question — "have I wrecked it?" — normally no. To leave the car that way, ring Petrol in Diesel then leave the motor switched off. Below, you will find what petrol really does inside a diesel, how far it might have gone, and how to stop it happening to you a second time.
The engine and petrol in a diesel: what goes on
Diesel has two jobs on its way through an engine. It protects to begin with, and only then does it burn. Made to extremely fine clearances, the fuel injectors and your pump rely on the diesel moving through them to stop their surfaces wearing against one another.
The second task petrol doesn't do at all, and the first it does poorly. The rattling comes from petrol being designed not to ignite when compressed, which is exactly the opposite of what a diesel needs. On top of that it is thinner than diesel, it strips out the lubrication the system hinges on, and any pump running on that blend is wearing itself.
Seen together, they make clear the shape the trouble has. Contact doesn't do the damage — circulation does. Any tank with petrol in it is a fuel problem. After your pump has been labouring on that petrol, a mechanical issue has begun: anything shed by a pump that's grinding travels downstream to your injectors with the fuel.
Four scenarios our technicians see around Little Knowle: how bad is petrol in a diesel?
Fuelled, and never started: no case is better. Being on a forecourt is what makes this the case: elsewhere, your car has been driven there to begin with. With the petrol kept in that tank alone, it is drained and cleaned right where it stands, and nothing more is needed.
Started for a second, or only your ignition on. With your system primed, the fuel lines and filter now hold petrol that has come from that tank. That is generally still a straightforward job — a drain, a flush, and the filter seen to.
Those few miles driven meant your pump working on fuel weakened by petrol the whole way. The work is that tank, the fuel lines, your filter and fresh fuel through the entire system, and how hard the car was driven matters as much as how far. The school run to St Peter's Church of England Primary School is one thing. Very different again: a trip to Exeter, under 15 miles away, or some mileage on the M5, under 10 miles from Little Knowle, where the motor kept labouring hard.
Driven until it complained. Knocking, an uneven idle, smoke, a throttle that has gone soft. The fuel is not acting like diesel any more, and your engine is telling you. Leave it wherever it has stopped: a lay-by, a side street, the verge on Bridge Road. What goes first is still the drain and flush, and that sorts it out, with long-term damage very uncommon if a car is stopped soon.
Myths Little Knowle drivers hear about petrol in a diesel
Myth: "Fill it the rest of the way with diesel and it'll be fine." It will not. Topping up takes out nothing; it gives you a bigger tank of the same mixture. The assumption behind that guidance — that diesel fuel systems tolerate petrol by percentage — is wrong.
"Newer diesels can handle a little petrol" — a myth, and nearer the opposite. A modern diesel runs its fuel through more precise parts at higher pressure, which makes the lubrication count more, not less.
"It starts, it drives, and so no harm done" — the myth that catches most people than any other. Diesel in a petrol motor normally means a motor that will not run: the driver stops, and so does the harm. Nothing seems to have happened when a diesel fed petrol fires up, ticks over and drives away, as it usually does; meanwhile the pump grinds. Running does not mean fine.
Myth: "Add some two-stroke oil and drive the vehicle home." It's an old workaround for a different problem. The petrol is still inside the tank afterwards, and whatever it has weakened isn't put back.
Once the engine has been run, part of the petrol is in your filter and the lines, not the tank — and your next start sends it right back through your pump. So the myth "drain your tank yourself and you're sorted" does not hold. Also, a can of petrol filled at the kerbside is genuinely hazardous.
Why petrol in a diesel occurs at all
It is seldom carelessness, and no one does it on purpose. The forecourt makes it easy: the petrol nozzle is the narrower of the two, and it slides into a diesel filler with almost no resistance, whilst a diesel nozzle generally won't go into a petrol car at all. So the error runs one way.
It happens when habit and your car stop matching. Courtesy car, hire car, or a vehicle that is new. Two vehicles on one drive, one petrol, one diesel. The pumps in a different order on a familiar forecourt. A train to catch, and a rushed fill en route to Exmouth. Precisely the moment it occurs: after years of driving petrol, a driver fills a diesel Volkswagen Golf for the first time. Add a back seat full of children, a phone call or rain, and habit takes over.
How to avoid petrol in a diesel at your next fill-up in Little Knowle
- Green for unleaded and black for diesel is usual in the UK — yet not on each forecourt. Go by the label on the petrol pump, not the colour.
- The first fill in a strange vehicle is the time to check your filler flap — inside it, or on the cap, plenty of cars state which fuel they take.
- Mark the key. In a house with one of each, a coloured fob or a sticker on the diesel's key does more than any amount of intending to remember.
- Before the nozzle comes off the petrol pump the first time you fuel a hired or new vehicle, say "diesel" out loud. Silly, yes, but it does the trick.
- 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.
- Some diesels come with a filler designed to refuse a petrol nozzle, and devices you can add are available for motors without one. Such an inhibitor helps up to a point — as a backstop, not a reason to stop reading the pump.
- The moment you realise, stop: less petrol inside that tank makes a thinner mix. What to do next doesn't change, though — still don't crank it.
Put petrol in a diesel in Little Knowle already?
Then the order of things is short. Leave it unstarted, with the ignition switched off too. The staff at the forecourt — whether at Pace itself or wherever you filled up — will usually help roll it away from the petrol pump if you ask. Next, 0333 366 0103. We'll ask what went in, roughly how much, and if it's been run.
Corrosion and deposits are the problem with AdBlue, where petrol brings lost protection. So if it was AdBlue, say so — and see its own Little Knowle page.
Little Knowle petrol in a diesel jobs: why one costs more than another
Four separate jobs sit behind the four scenarios above — which is why there's no fair single quote. Chiefly, the cost shifts with which one you are in. Where your car is counts too, and whether our van can safely reach it, after the share of petrol to what the tank holds.
Ahead of any quote, not after, come three questions: the fuel that got in, its amount, and if it's run. That's why. Given those replies, there is a straight figure instead of a range.
About Little Knowle, for a moment
Little Knowle is a coastal locality in Devon, situated near the towns of Budleigh Salterton and Knowle, with Kersbrook to the east. Little Knowle lies at an elevation of 39 metres, close to the South West Coast, and is approximately 11 miles from the city of Exeter. Little Knowle has a population of around 1891 residents, predominantly living in detached housing.
Fuel drain cover around Little Knowle and across Devon
Petrol in diesel jobs in Little Knowle — part of the EX postcode area — go to teams that also cover the spots around it, Kersbrook, Budleigh Salterton and Knowle included. The car doesn't need to come to us: we drain at a forecourt, in a supermarket car park, in a lay-by or on your own driveway.
In Little Knowle and still at the petrol pump?
Then you're in the best position there can be. Keep it off. Call.