Should You Worry? Petrol in a Diesel Car in Alton
Likely less than you already are — provided nobody has started it. Till your ignition primes the pump, your starter cranks, or your car is driven, petrol in a diesel tank just sits there and does no harm. Which makes the truthful reply to that first Alton question — "have I wrecked it?" — normally no. To keep the vehicle that way, ring Petrol in Diesel and leave the engine switched off. What petrol actually does to a diesel, how to judge how far it's travelled, and how to stop it from happening a second time: that is the remainder of this page.
Inside the motor: what petrol in a diesel really does
Diesel has two tasks on its way through an engine. It protects first, and after that does it burn. Designed to extremely fine tolerances, your injectors and the pump depend on the diesel flowing through them to keep their surfaces from wearing against one another.
Of these two jobs, petrol manages the first badly and the second never. It's runnier than diesel and removes the protection the fuel system hinges on, so a pump running on a petrol blend is a pump wearing itself. And petrol is designed to resist igniting under compression, which is the opposite of what a diesel needs from its fuel. That's where the knocking comes from.
Together, those leave the shape of the problem clear. The damage is done by movement, not by contact. Where the petrol is only inside your tank, it's a fault of fuel, nothing more. Once the pump has been working on that petrol, a mechanical issue has begun: whatever is shed by a pump that's grinding is carried downstream to the fuel injectors with your fuel.
How serious is petrol in a diesel? Four situations our technicians see around Alton
Filled up, and not started: no case is better. Being at a forecourt is what makes this the case: elsewhere, the vehicle has been driven there to begin with. With that petrol held inside your tank alone, it is drained and flushed on the spot, and nothing more is needed.
Started for a moment, or only your ignition on. With the system primed, the lines and filter now hold petrol that has come from the tank. Normally nothing more than draining, purging and sorting your filter, and so still simple.
Driven a couple of miles. Now your pump has spent these miles running on weakened fuel. How hard your car was driven matters as much as how far, and the work takes in that tank, the lines, your filter and fresh fuel through the whole circuit. Short trips, such as the school run to Saint Lawrence Church of England Primary School, are one matter. A run as far as Winchester, under 25 miles away, is a very different task. So is any miles on the M3, under 10 miles from Alton, where your engine has been running hard the whole time.
It protested, and only then stopped: smoke, rattling, a throttle gone soft, an idle gone uneven. What you are hearing is the motor reporting fuel that no longer runs like diesel. Leave it where it stops: a lay-by, a side street, the verge on High Street. Permanent damage is very unusual when a vehicle is pulled over early, and the drain and flush-through that still go first sort it out.
Petrol in a diesel myths Alton motorists hear
Myth: topping up to full with diesel makes it fine. It doesn't. Topping up takes out nothing; it gives you a fuller tank of the same mix. The idea behind the advice — that diesel fuel systems accept petrol by percentage — is wrong.
Myth: "A current diesel can cope with a bit of petrol." If anything, the reverse. At higher pressure, through more precise components: that is how a newer diesel handles its fuel, so the protection matters more, not less.
"It starts, it drives, and so no harm done" — the myth that catches most people than any other. The driver of a petrol motor fed diesel normally stops, because 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, which it usually will; meanwhile the pump wears. Running is not the same as fine.
An outdated workaround for a distinct issue is behind this one. Myth: "Add some two-stroke oil and drive the vehicle home." None of what petrol weakened gets put back by it — and later, your tank still contains that petrol.
"Drain it yourself and you're sorted" — a myth, since after it has been running some petrol sits in the filter and lines, ready to go right back through the pump at the next start. Besides, petrol drained into a can by the road is genuinely dangerous.
Why petrol in a diesel happens so easily
Nobody does it on purpose, and it is rarely carelessness. A diesel nozzle generally will not go into a petrol motor, but the slimmer petrol nozzle goes into the filler of a diesel almost without resistance — so forecourts make this one error straightforward, and just in one direction.
It occurs when routine and the vehicle stop matching. Courtesy car, hire car, or a vehicle that's new. Households running one of each, petrol and diesel. Your normal forecourt, its pumps suddenly in a different order. Fuelling up in a hurry on the way to the nearest station, with a train to catch. The first fill-up in a diesel Volkswagen Passat after years of driving petrol is precisely the moment it happens. Throw in a back seat full of children, a phone call or rain, and habit wins.
How to prevent petrol in a diesel on your next fill-up around Alton
- The label is what matters, and so read the petrol pump rather than the colour: in the UK unleaded handles are usually green and diesel black, yet not on each forecourt.
- Inspect your filler flap. Plenty of motors state the fuel inside the flap or on the cap. Look at it on the first fill in any motor you don't know.
- One of each in the household? Mark the key to the diesel — a bright fob, a sticker — because intending to remember is not enough.
- Before the nozzle leaves the pump the first time you fuel a hired or new vehicle, say "diesel" out loud. Silly, perhaps, yet it does the trick.
- Thinking about something else is when this becomes an easy mistake to make, so put your phone away then keep your mind on the petrol pump.
- Some diesels have a filler designed to reject a petrol nozzle, and devices you can add are available for cars without one. Such an inhibitor helps up to a point — as a safety net, not a reason to stop checking the pump.
- The moment you notice, stop: less petrol in that tank means a weaker mix. What to do next does not change, though — still do not start the car.
Already put petrol in a diesel in Alton?
Then, there is only a short order of things. Leave it unstarted, with your ignition switched off too. If you're still on the forecourt — the nearest petrol station or anywhere else — ask the attendants to help you roll the vehicle away from the pump. Next, 0333 366 0103. We will ask what went in, roughly how much, and if it's been run.
Say so if it was AdBlue rather than petrol: it is a different problem, with its own page for Alton, since AdBlue brings corrosion and deposits rather than lost protection.
Why one petrol in a diesel job in Alton costs more than another
Four different tasks lie behind the four scenarios above — which is why there is no honest single price. Mostly, your cost shifts with which situation you're in. After that it is the share — how much petrol was put in against how much that tank takes — and after that where the vehicle is and whether our van can get to it safely.
Three queries come first, before any quote, rather than after — what got in, how much, has it run — and this is the reason. A range turns into a straight figure when those answers are in.
About Alton, for a moment
Alton is a town situated in the valley of the River Wey in Hampshire, with a riverside setting and an elevation of around 105 metres. Alton lies approximately 44 miles south-west of London and 16 miles east of Winchester, making it a commuter town for both cities. Alton has a mix of housing types, but semi-detached homes are particularly prevalent in the area. Alton is surrounded by smaller neighbourhoods, including Mount Pleasant, Newtown, and Wilsom.
Across Hampshire and around Alton: fuel drain cover
Mount Pleasant, Newtown and Wilsom are among the places near Alton that the same teams work, answering petrol in diesel calls across Alton's GU postcode area. A forecourt, a supermarket car park, a lay-by or your own drive are all locations we drain, and your vehicle does not need to move to us.
Still at the pump around Alton?
The best place there is, then — that's where you are. Keep it off. Ring.