Dibden: Petrol in a Diesel Car? How Worried to Be
Probably less than you are now — provided nobody has started it. Until your ignition primes your pump, your starter cranks, or your vehicle is driven, petrol in a diesel tank simply sits there and does no harm. Which makes the honest reply to that first Dibden question — "have I ruined it?" — usually no. Keep it like that: leave the engine off and ring Petrol in Diesel. Read on for three things: the effect petrol has inside a diesel engine, the signs of how far it has spread, and ways to make sure you never do it again.
Petrol in a diesel: what does it do to your engine?
Two tasks fall to diesel on its journey through a motor. It protects first, and only then does it burn. Extremely fine clearances go into the injectors and your high-pressure pump, and only the diesel running through keeps their surfaces from grinding together.
Of these two jobs, petrol manages the first badly and the second not at all. Being less viscous than diesel, petrol strips away the lubrication a fuel system needs, leaving a pump on the blend wearing itself. It is equally made to resist igniting under compression — the reverse of what a diesel needs — which is where you get the knocking.
Taken together, they show what shape the problem has. Contact does not do the harm — circulation does. Where the petrol is only in that tank, it's an issue of fuel, nothing more. After your pump has been labouring on that petrol, a mechanical fault has started: whatever is shed by a pump that is grinding travels onward to your injectors with the fuel.
Petrol in a diesel around Dibden: how serious is it? Four cases
Fuelled up, never started. The best case there is. On a forecourt, and really only there, the petrol is still confined to your tank — since everywhere else the vehicle was driven to get to it. The task is emptying and rinsing on the spot.
The ignition turned on, or a short start. Petrol has come out of your tank and got to your filter and the lines, because your system has been primed. Still normally straightforward: drain, flush, and the fuel filter dealt with.
Driven a few miles. Now your pump has spent those miles working on thinned fuel. Tank, lines, filter, then fresh fuel run through the entire circuit: that's the work, and the way the car was driven matters as much as the distance. Short trips, like the school run to Orchard Junior School, are one thing. Very different again: a run to Southampton, under 3 miles away, or some miles on the M271, under 5 miles from Dibden, where your engine never stopped working hard.
Driven on till it protested — clattering, smoke, a lumpy idle, a soft throttle. That's your engine telling you its fuel has stopped acting like diesel. Leave it where it stops: a lay-by, a quiet street, the verge on Claypits Lane. Lasting damage is very rare when a vehicle is stopped early, and the fuel drain and flush that still come first take care of it.
What Dibden people get told about petrol in a diesel — and the stories in it
"Top it up the rest of the way with diesel and it will be fine" — a myth. It won't. Nothing is removed by topping up — you're left with a fuller tank, still the same mix. The idea behind the advice — that diesel fuel systems tolerate petrol by percentage — is wrong.
"Newer diesels can handle a little petrol" — a myth, and closer to the opposite. A modern diesel sends its fuel through finer components at higher pressure, which makes the lubrication count more, not less.
Myth: "If it starts and drives, there's no damage done." This is the one that catches motorists. The motorist of a petrol engine fed diesel normally stops, since it will not run, and the harm stops there. A diesel fed petrol usually starts, ticks over and drives away as if nothing has happened, while 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 problem. What petrol has weakened remains diluted, and the petrol remains inside that tank regardless.
If the motor has been run, part of that petrol is in the fuel filter and your lines, not the tank — and the next start pulls it right back through your pump. So the myth "drain the tank yourself and you are sorted" doesn't hold. Emptying petrol into a can by the kerbside is also genuinely hazardous.
Why petrol in a diesel happens so easily
It is rarely carelessness, and no one does it on purpose. A diesel nozzle generally won't fit a petrol vehicle, but the narrower petrol nozzle goes into the filler of a diesel almost without resistance — so forecourts make this one mistake easy, and just in that direction.
It happens when routine and your car stop matching. A new motor, a hire car or a courtesy car. Households running one of each, petrol and diesel. The pumps in a different order on a well-known forecourt. A train to catch, and a rushed fill en route to Southampton Town Quay. Precisely the moment it takes place: after years of driving petrol, someone fills a diesel Volkswagen Tiguan for the first time. Throw in a back seat full of kids, a phone call or rain, and the hand wins.
Avoiding petrol in a diesel next time you fill up around Dibden
- The label is what matters, and so check the pump rather than the colour: in the UK unleaded handles are normally green and diesel black, yet not on each forecourt.
- Plenty of vehicles state the fuel type inside your filler flap or on the cap, so check there on your first fill in any motor you don't know.
- A coloured fob or a sticker on the diesel's key achieves more than any amount of meaning to remember, in a household with one of each.
- Before the nozzle leaves the pump the first time you fill a hired or new vehicle, say "diesel" out loud. Silly, perhaps, yet it does the trick.
- Mistakes like this are straightforward to make while your mind is on something else, and 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 reading the pump.
- Less petrol means a weaker mixture, and so stop as soon as you notice — while remembering that your next stage is unchanged. It is still not to start the vehicle.
Put petrol in a diesel in Dibden already?
Then the order of things is brief. Don't turn your ignition on, and do not start it. If you are still at the forecourt — the nearest petrol station or anywhere else — ask the staff to help you roll it away from the petrol pump. What went in, roughly how much, and whether it's run: tell us that when you call 0333 366 0103.
Corrosion and deposits are the issue with AdBlue, where petrol means lost protection. So if it was AdBlue, say so — and see its own Dibden page.
Why one petrol in a diesel job in Dibden costs more than another
The four situations above are four separate tasks, so no single quote for this would be fair. Mostly, your cost moves with which one you are in. Where the vehicle is matters too, and whether a technician can safely get to it, after the ratio of petrol to what that tank holds.
What went in, how much, and whether it's run — three queries our engineers ask before costing, not after, for exactly that reason. The replies turn a range into a straight figure.
About Dibden
Dibden is a small village on the coast of Hampshire, situated near the city of Southampton and close to the New Forest. Dibden has a population of around 1696 people and is characterized by its terraced housing. Dibden sits at a low elevation of 11 metres above sea level, looking out over the water towards the nearby town of Hythe.
Across Hampshire and in Dibden: fuel drain cover
Petrol in diesel calls in Dibden — part of the SO postcode area — go to teams that also cover the locations around it, Applemore, Hythe and Dibden Purlieu included. We drain wherever your vehicle is — your own drive, a lay-by, a supermarket car park, a forecourt — so it does not have to come to us.
At the pump in Dibden, right now?
Nothing beats it: that is where you are. Leave it switched off, and ring.