Should You Worry? Petrol in a Diesel Car in Cottenham Park
Less than you probably are, if it has not been started. Petrol sitting in a diesel tank does nothing to the motor till something pulls it through your fuel system — your ignition priming the pump, your starter, or driving on its own. So the fair answer to the first question everyone in Cottenham Park asks, "have I ruined it?", is generally no. Leave the engine off then call Petrol in Diesel — that keeps it that way. Further down, you will find what petrol really does inside a diesel, how far it might have got, and how to stop it happening to you a second time.
Petrol in a diesel: what does it do to your engine?
Diesel has two tasks on its way through a motor. It lubricates first, and only then does it burn. Very fine clearances go into your injectors and your high-pressure pump, and only your diesel flowing through stops their surfaces grinding together.
Petrol does the first task badly and the second not at all. The knocking comes from petrol being made 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 protection the system rests on, and any pump working on that blend is wearing itself.
Put these together and the shape of the trouble is clear. Contact doesn't do the damage — circulation does. All a tank with petrol in it amounts to is a fuel issue. Whatever a worn pump sheds goes on, carried by the fuel, into the fuel injectors further along, which is why a pump that has worked on that petrol is where a mechanical issue starts.
Petrol in a diesel around Cottenham Park: how serious is it? Four cases
Filled but never started — as good as it gets. On a forecourt, and truly only there, that petrol is still limited to the tank — since everywhere else the car was driven to get to it. The job is draining and cleaning on the spot.
Ignition on, or started for a second. The system has been bled, and so petrol has left your tank and got to the filter and the lines. That's generally still a straightforward task — a drain, a flush, and the filter dealt with.
The pump has spent a few miles on weakened fuel — that's what driving the vehicle does. Miles is only half of that; how hard it was driven counts equally. Either way this work runs to that tank, the lines, the fuel filter and clean fuel through the whole system. A school run to Hollymount School is one matter. Any distance on the M4, under 10 miles from Cottenham Park, means the motor has worked hard throughout, and a run to Westminster, under 10 miles away, is a very different task as well.
Driven until it protested. Clattering, a lumpy idle, smoke, a throttle that has gone soft. The fuel is not behaving like diesel any more, and your engine is telling you. Leave it wherever it has stopped: a lay-by, a quiet street, the verge on Cambridge Road. A vehicle stopped soon very rarely has long-term damage, as the drain and the flush, which still go first, sort it out.
What Cottenham Park motorists get told about petrol in a diesel — and the myths in it
"Top it up the rest of the way with diesel and it will be fine" — a myth. It will not. Nothing is removed when you top up — your tank simply holds more of the same blend. A diesel fuel system doesn't accept petrol by percentage in the way that advice supposes.
Myth: "A newer diesel can cope with a bit of petrol." If anything, the reverse. Protection matters more on current diesels, not less, because their fuel passes through more precise components at higher pressure.
This is the one that fools drivers. Myth: "If it starts and drives, there's no harm done." Any petrol engine fed diesel usually will not run, and so the driver stops and the harm stops with them. Feed petrol to a diesel and it usually starts, idles and drives away like nothing has happened — all the while its pump is wearing. Running is not the same as fine.
An old fix for a separate fault is behind this one. Myth: "Add some two-stroke oil and drive it home." None of what petrol diluted is put back by it — and later, that tank still holds the petrol.
"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 right back through your pump on the next start. Also, a can of petrol filled by the roadside is genuinely risky.
Why petrol in a diesel takes place so easily
Nobody does it on purpose, and it's rarely carelessness. The forecourt makes it easy: the petrol nozzle is the smaller of the two, and it slips into a diesel filler with almost no resistance, while a diesel nozzle mostly will not go into a petrol vehicle at all. So the error runs one way.
It occurs when habit and the car stop matching. Courtesy car, hire car, or a vehicle that is new. Two cars on one driveway, one petrol, one diesel. The pumps in a different order on a well-known forecourt. A train to catch, and a hurried fill en route to Raynes Park. Precisely the moment it happens: after years of driving petrol, a driver fills a diesel Renault Megane for the first time. Add a back seat full of kids, a phone call or rain, and the hand takes over.
Next time you fill up in Cottenham Park: avoiding petrol in a diesel
- Not every forecourt in the UK keeps to green for unleaded and black for diesel, though most usually do. Read the pump's label; the colour is only a hint.
- In a car you don't know, look inside the flap over the filler or at the cap before the first fill: many vehicles state the fuel type there.
- One of each in the household? Label your key to the diesel — a bright fob, a sticker — because intending to remember is not enough.
- Say it before you lift it. On your first fill in a new or hired car, say "diesel" out loud before you take the nozzle off the petrol pump. It seems daft and it does the trick.
- Thinking about something else is when this becomes an easy mistake to make, so tuck your phone away and keep your mind on the petrol pump.
- Up to a point, a misfuel inhibitor helps: some diesels come with a filler built to refuse a petrol nozzle, and aftermarket devices are available for the remainder. Count it as a safety net, then keep reading the petrol pump.
- Noticing it halfway? Stop at once. A weaker mixture results from less petrol in your tank, yet your next step stays the same: don't start it.
Already put petrol in a diesel around Cottenham Park?
In that case, there's only a short order of things. Do not fire it up, and don't switch the ignition on. Still on the forecourt, at Shell or anywhere else? Ask the attendants to help you push the car away from the pump. Phone 0333 366 0103 next, with three answers — your fuel, the approximate volume, and whether it has run.
AdBlue, not petrol? Then say so. Corrosion and deposits, not lost protection, make it a different issue — Cottenham Park has a page just for it.
One petrol in a diesel task around Cottenham Park costs more than another. Why?
The four situations above are four different jobs, so no single price for this would be fair. Chiefly, the cost moves with which situation you are in. Two things follow that: the petrol that got in as a share of what your tank holds, then the spot the vehicle is in and whether a technician can get to it safely.
What went in, how much, and whether it's run — three queries our engineers ask before costing, not after, for precisely that reason. Given those answers, there is a straight figure instead of a range.
About Cottenham Park itself
Cottenham Park is a suburban area in southwest London, situated approximately 7.9 miles from central London. Cottenham Park is characterised by its predominantly flat housing stock, with many residents commuting to nearby Westminster. Cottenham Park sits near several other suburban areas, including Copse Hill and Raynes Park, and is close to the Crooked Billet junction. Cottenham Park has a population of around 9502 people, living in a relatively low-lying area at an elevation of 23 metres.
Across Greater London and around Cottenham Park: fuel drain cover
Our vans answering petrol in diesel jobs in Cottenham Park, in the SW postcode area, also work the places near it, Copse Hill, Raynes Park and Crooked Billet among them. Our engineers drain wherever your car is — your own driveway, a lay-by, a supermarket car park, a forecourt — so it never needs to come to us.
Cottenham Park: still at the petrol pump?
Then you're in the best spot there is. Turned off it remains; then call.