Should You Worry? Petrol in a Diesel Car in Comberton
Likely less than you are now — as long as nobody has started it. Petrol resting in a diesel tank does nothing to the engine till something draws it through your fuel system — your ignition priming the pump, the starter, or driving on its own. So the truthful answer to the first question everyone around Comberton asks, "have I ruined it?", is normally no. Leave your engine off then ring Petrol in Diesel — that keeps it that way. Further down, this page sets out what petrol actually does inside a diesel, how far it might have got, and how to stop it happening to you a second time.
Inside the engine: what petrol in a diesel does
Passing through an engine, diesel is doing two jobs at the same time. It burns, and before it combusts it lubricates. Built to extremely fine tolerances, your injectors and your pump depend on your diesel flowing through them to stop their surfaces wearing against one another.
Petrol does the first job badly and the second not at all. The rattling comes from petrol being made not to ignite when compressed, which is precisely the opposite of what a diesel needs. On top of that it is thinner than diesel, it strips away the lubrication the system hinges on, and any pump working on such a mixture is wearing itself.
Seen together, they make clear what shape the problem takes. It's circulation that does the damage, not contact. Where the petrol is only inside that tank, it's an issue of fuel, nothing more. After the pump has been working on that petrol, a mechanical fault has begun: whatever is shed by a pump that's wearing down is carried onward to your injectors with the fuel.
Four situations our technicians see in Comberton: how serious is petrol in a diesel?
Filled but never started — the best it gets. Being at a forecourt is what makes this the case: elsewhere, the vehicle has been driven there to begin with. With the petrol held in that tank alone, it's drained and rinsed on the spot, and nothing more is needed.
Started for a second, or only your ignition on. Petrol has come out of your tank and got to your filter and the fuel lines, because the fuel system has been bled. That is usually still an easy job — a drain, a flush, and the filter seen to.
Those few miles on the road meant your pump working on fuel diluted by petrol the whole way. Tank, lines, filter, then fresh fuel put through the whole system: that is the work, and the way your car was driven matters as much as the distance. The school run to Comberton Primary School is one thing. Very different a second time: a run to Worcester, under 15 miles away, or any miles on the M5, under 10 miles from Comberton, where the motor kept running hard.
Driven till it complained. Knocking, a ragged idle, smoke, a throttle that has gone soft. The fuel isn't behaving like diesel any more, and your engine is telling you. Leave it where it stops: a lay-by, a quiet street, the verge on Comberton Avenue. What comes first is still the fuel drain and flush, and that takes care of it, with lasting damage very unusual when a vehicle is pulled over quickly.
Comberton people and that petrol in a diesel stories they hear
"Top it up the rest of the way with diesel and it will be fine" — a myth. It will not. Nothing comes out when you top up — your tank just holds more of the same mixture. The assumption behind the advice — that diesel fuel systems accept petrol by percentage — is wrong.
Myth: a current diesel copes with a bit of petrol. Rather, the opposite. A modern diesel sends its fuel through more precise components at higher pressure, which makes the lubrication count more, not less.
The myth that catches drivers off guard: if it starts and drives, it must be unharmed. The driver of a petrol engine fed diesel usually has no choice but to stop, since it will not run, and the damage stops there. A diesel fed petrol normally starts, ticks over and drives away as if nothing has happened, while your pump wears. A running engine doesn't mean fine.
An outdated workaround for a separate issue lies behind this one. Myth: "Add some two-stroke oil and drive it home." The petrol is still inside your tank after that, and whatever it has weakened isn't put back.
"Drain it yourself and you are sorted" — a myth, since after it's been running some petrol sits in the fuel filter and lines, waiting to go straight back through the pump at your next start. It's also really hazardous to drain petrol into a can at the kerbside.
Petrol in a diesel: how does it occur?
On purpose? Never. Through carelessness? Rarely, if ever. A diesel nozzle generally won't go into a petrol car, yet the narrower petrol nozzle goes into the filler of a diesel almost without resistance — so forecourts make this one error easy, and only in that direction.
Routine and the car getting out of step is when it occurs. Any motor that's new to you — hired, on loan as a courtesy car, or just bought. A household with one petrol and one diesel on the driveway. A well-known forecourt with the pumps in a different order. A train to catch, and a rushed fill en route to Kidderminster. Exactly the moment it happens: after years of driving petrol, someone fills a diesel Volkswagen Golf for the first time. Add a back seat full of kids, a phone call or rain, and habit wins.
Preventing petrol in a diesel next time you fill up around Comberton
- Green for unleaded and black for diesel is normal in the UK — but not on each forecourt. Trust the label on the petrol pump, not the colour.
- Many motors state the fuel inside your filler flap or on the cap, so check there on the first fill in a vehicle you don't know.
- A coloured fob or a sticker on the diesel's key does more than any amount of intending to remember, for a house with one of each.
- It seems silly and it does the trick: on your first fill in a new or hired car, say "diesel" aloud before you take the nozzle off the petrol pump.
- Mistakes like this are simple to make whilst your mind is on something else, so your phone goes away.
- A misfuel inhibitor helps, up to a point. Some diesels come with a filler built to block a petrol nozzle, and add-on devices exist for cars without one. They are a safety net, not a reason to stop reading the pump.
- Stop as soon as you notice. Less petrol inside your tank makes a thinner mix. It doesn't change what to do next, which is still not to crank it.
Put petrol in a diesel in Comberton already?
The order of things is brief, then. Leave it unstarted, with your ignition off too. If you're still at the forecourt — Texaco or anywhere else — ask the attendants to help you push it clear of the pump. What went in, about how much, and whether it's run: tell us those when you ring 0333 366 0103.
Corrosion and deposits are the issue with AdBlue, whereas petrol means lost protection. So if it was AdBlue, say so — and read its own Comberton page.
Why one petrol in a diesel task in Comberton costs more than another
There is no honest single quote for this, since the four situations above are four different tasks. The situation itself does most of the work of moving the cost. Where your car is counts too, and whether a technician can safely get to it, after the share of petrol to what your tank takes.
What went in, how much, and if it has run — three queries our engineers ask before costing, not after, for exactly that reason. With the answers, there is a straight figure rather than a range.
About Comberton itself
Comberton is a suburban area in Worcestershire, situated near the River Severn at an elevation of around 50 metres. Comberton lies approximately 13 miles from Worcester and 108 miles from London, with nearby places including Offmore Farm, Spennells, and Aggborough. Comberton has a population of around 4128 people, predominantly living in semi-detached housing. Comberton is characterized by its riverside setting, which influences its local environment and community.
Fuel drain cover in Comberton and across Worcestershire
Offmore Farm, Spennells and Aggborough are among the places near Comberton that the same vans work, answering petrol in diesel call-outs across Comberton's DY postcode area. A forecourt, a supermarket car park, a lay-by or your own drive are all locations our technicians work, and your car does not need to come to us.
Comberton: still at the petrol pump?
Then you're in the best place there can be. Keep it off. Call.