Petrol in a Diesel Car in Petersham: How Worried Should You Be?
Provided it has not been started, worry less than you likely are. Petrol resting in a diesel tank does nothing to the engine until something pulls it through the system — the ignition priming your pump, the starter, or driving on its own. So the honest answer to the first query everyone in Petersham asks, "have I wrecked it?", is generally no. Petrol in Diesel is who to ring, with the engine left off, so it remains that way. The remainder of this page explains what petrol really does to a diesel, how to tell how far it has got, and how to make sure it doesn't happen to you a second time.
What petrol in a diesel does to the motor
Two tasks fall to diesel on its route round a motor. Before it combusts, it lubricates — and then it ignites. Very fine tolerances go into the injectors and the high-pressure fuel pump, and just your diesel flowing through stops their surfaces grinding together.
The second task petrol does not do at all, and the first it does poorly. Being less viscous than diesel, petrol strips away the lubrication a fuel system needs, leaving a pump running on the blend wearing itself. It's also made to resist igniting under compression — the opposite of what a diesel needs — which is why you hear the rattling.
Seen together, they show what shape the trouble has. It's circulation that does the harm, not contact. Where the petrol is only in that tank, it is a problem of fuel, nothing more. After the pump has been labouring on that petrol, a mechanical fault has started: anything shed by a pump that is grinding is carried downstream to the injectors with your fuel.
Petrol in a diesel around Petersham: how serious is it? Four cases
Filled up, never started. The best case there can be. At a forecourt, and truly only there, the petrol is still confined to that tank — since anywhere else the vehicle was driven to get to it. The task is draining and purging on the spot.
Started for a second, or just your ignition on. Petrol has left the tank and reached your filter and the lines, because the fuel system has been primed. Still usually easy: drain, flush, and the fuel filter seen to.
Those few miles on the road meant your pump working on fuel diluted by petrol throughout. The work is that tank, the fuel lines, your filter and fresh fuel through the whole system, and how hard the car was driven counts as much as how far. On the school run to The Russell Primary School, the distance is small. Any mileage on the M4, under 3 miles from Petersham, means the motor has worked hard throughout, and a run to Westminster, under 10 miles away, is a very different job as well.
Knocking, a lumpy idle, smoke, a throttle gone soft: driven until it complained. What you are hearing is your engine signalling fuel that no longer acts like diesel. Whether it is the verge on Petersham Road, a lay-by or a side road, stop where you are and leave it. The fuel drain and flush-through still come first, and they take care of it: when a car is pulled over soon, long-term damage is very uncommon.
Stories Petersham drivers hear about petrol in a diesel
"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. Percentage isn't how a diesel fuel system copes with petrol, however much that guidance assumes.
If anything, the opposite holds. Myth: "A newer diesel can cope with a bit of petrol." Finer parts and higher pressure are how a newer diesel runs its fuel, and that makes the lubrication count more, not less.
"It starts, it drives, and so no harm done" — the myth that trips up more motorists than any other. A petrol motor fed diesel normally will not run, and so the driver stops and the damage stops with them. While your pump wears, a diesel fed petrol normally starts, idles and drives away as if nothing has happened. Being able to run is not proof of being fine.
Myth: "Add some two-stroke oil and drive the car home." It is an outdated fix for a separate issue. It does not put back what petrol has weakened, and that petrol is still in your tank after that.
The next start draws petrol back round your pump out of your lines and the fuel filter, where some of that sits once your engine has run. That is why draining the tank yourself does not leave you sorted — a myth. And, a can of petrol drained at the roadside is genuinely dangerous.
How does petrol in a diesel happen?
A careless moment is rarely the cause, and no one means to do it. 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, while a diesel nozzle mostly will not go into a petrol car at all. So the error runs one way.
Habit and the car falling out of step is how it takes place. A motor that's new to you — a hire car, on loan as a courtesy car, or brand new. Two vehicles on one driveway, one petrol, one diesel. A forecourt you know, but with its pumps arranged differently. Filling up in a hurry en route to Richmond, with a train to catch. Years of petrol vehicles behind you, a diesel Volkswagen Golf in front of you on the forecourt for its first tank — that is when. With rain, a call arriving, or a car full of children to deal with, your hand simply does what it has always done.
Next time you fill up in Petersham: avoiding petrol in a diesel
- The label is what counts, so read the petrol pump instead of the colour: in the UK unleaded handles are normally green and diesel black, yet not on each forecourt.
- In a car you don't know, look inside the flap over the filler or at the cap before your first fill: many motors print the fuel there.
- Label your key. In a house with one of each, a coloured fob or a sticker on your diesel's key does more than any amount of intending to remember.
- Before the nozzle comes off the petrol pump the first time you fill a hired or new vehicle, say "diesel" out loud. Silly, perhaps, but it does the trick.
- Mistakes like this are easy to make whilst your mind is on something else, so your phone goes away.
- Up to a point, a misfuel inhibitor helps: some diesels come with a filler built to reject a petrol nozzle, and aftermarket devices are available for the remainder. Count it as a safety net, then keep reading the petrol pump.
- Spotting it mid-fill? Stop there and then. A thinner blend follows from less petrol inside your tank, but the next step remains the same: don't crank it.
Put petrol in a diesel in Petersham already?
The order of things is short, then. Starting it is out, and so is switching on the ignition. The attendants at the forecourt — whether at Shell itself or wherever you filled up — will normally help push it away from the petrol pump if you ask. Phone 0333 366 0103 next, with three facts — your fuel, the approximate quantity, and if it's run.
AdBlue, not petrol? Then say so. Corrosion and deposits, not lost protection, make it a different fault — Petersham has a page all for it.
One petrol in a diesel job around Petersham costs more than another. Why?
There's no fair single quote for this, since the four situations above are four separate tasks. Mostly, your cost shifts with which situation you're in. After that it's the ratio — how much petrol went in against how much that tank takes — and then where your car is and whether a van can reach it safely.
That is why our engineers ask three queries before quoting instead of after: what got in, how much, and if it's run. Those replies change a range into a straight figure.
About Petersham and where it is
Petersham is a small suburban area in southwest London, situated on the River Thames. Petersham sits at an elevation of 19 metres, with views across the river to the surrounding countryside. Petersham is characterised by its predominantly detached housing stock and is located near to Richmond, Ham, and Eel Pie Island. Petersham is a relatively small community, with a population of approximately 999 residents.
Across Greater London and around Petersham: fuel drain cover
Petersham waits in the TW postcode area, and the teams that answer petrol in diesel calls there work the spots around it as well — Richmond, Ham and Eel Pie Island among them. A forecourt, a supermarket car park, a lay-by or your own drive are all locations our engineers work, and the car does not need to come to us.
Still at the pump around Petersham?
In that case, you could not be in a better spot. Leave the vehicle turned off, and ring.