Symonds Green: Petrol in a Diesel Car? How Worried to Be
Likely less than you are now — provided nobody has started the car. Till your ignition primes your pump, the starter turns, or your car is driven, petrol in a diesel tank simply waits there and does nothing. Which makes the truthful reply to the first Symonds Green question — "have I ruined it?" — usually no. Leave the engine off and phone 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 gone, and how to stop it happening to you again.
The motor and petrol in a diesel: what happens
Two tasks fall to diesel on its route round a motor. Oiling comes before burning; it does both. The high-pressure fuel pump and the fuel injectors are built to extremely fine tolerances, and the diesel passing through them is what keeps those surfaces from grinding against each other.
The second job petrol doesn't 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 to wear itself. It's also made to resist igniting under compression — the reverse of what a diesel needs — which is where you get the clattering.
Combined, those leave the shape of the problem clear. Not contact but movement is what does the harm. Petrol in a tank is a fuel fault. Once the pump has been labouring on that petrol, a mechanical issue has started: whatever is shed by a pump that's grinding travels onward to the injectors with your fuel.
Symonds Green, petrol in a diesel: four situations, from mild to major
Filled up, and not started: no case is better. Just the tank has petrol in it, and so the job is clearing the tank and purging the fuel system where the vehicle stands. This scenario can only truly take place at a forecourt: anywhere else, your car got there by being driven.
Started for a second, or only the ignition on. Once primed, the system has drawn petrol from that tank up to the filter and your lines. That's usually still a simple job — a drain, a flush, and the filter seen to.
Driven a couple of miles. Now your pump has spent these miles labouring on diluted fuel. The work is that tank, the lines, the filter and fresh fuel through the entire system, and how hard the car was driven counts as much as how far. On the school run to Woolenwick Infant and Nursery School, the miles is small. Very different once more: a run to St Albans, under 15 miles away, or some distance on the A1(M), under a mile from Symonds Green, where the engine kept labouring hard.
Driven until it complained. Rattling, a lumpy idle, smoke, a throttle that has gone soft. That is the engine telling you its fuel no longer is behaving like diesel. Stop wherever you are — the verge on Blakeney Road, a lay-by, a side street — and leave the vehicle where it is. What comes first is still the drain and flush-through, and that takes care of it, with lasting damage very uncommon if a car is pulled over early.
Symonds Green drivers 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 is removed by topping up — you're left with a bigger tank, still the same mixture. The assumption behind the advice — that diesel fuel systems tolerate petrol by percentage — is wrong.
Myth: "A modern diesel can cope with a bit of petrol." If anything, the opposite. Protection matters more on current diesels, not less, because their fuel passes through more precise components at higher pressure.
One myth that catches drivers off guard: if it starts and drives, it must be unharmed. Any petrol engine fed diesel normally won't run, and so the motorist stops and the harm stops with them. Whilst your pump wears, a diesel fed petrol normally starts, idles and drives away as though nothing has happened. Being able to run isn't the same as being fine.
Not so: a two-stroke additive makes it safe to drive home. It is an old workaround, supposed for another issue. It doesn't put back what petrol has diluted, and the petrol is still inside that tank later.
Myth: "Drain that tank yourself and you're sorted." Once the motor has run, some of the petrol is no longer in that tank: it's in the fuel filter and the fuel lines, and it goes straight back through your pump at your next start. Also, a can of petrol drained at the roadside is genuinely dangerous.
How does petrol in a diesel happen?
It is seldom carelessness, and no one does it on purpose. The petrol nozzle is the narrower of the two and slides into a diesel filler with almost no resistance; a diesel nozzle mostly will not go into a petrol motor at all. The forecourt makes it simple, and the error runs one way.
When habit and the car stop matching, it takes place. Hire cars, courtesy cars, and cars that are new to you. A household with one petrol and one diesel on the driveway. Your usual forecourt, its pumps suddenly in a different order. Rushing for a train outside Stevenage and filling up en route. Years of petrol motors behind you, a diesel Renault Clio in front of you at the forecourt for its first tank — that's when. The hand repeats what it has always done when you add rain, a phone call or a back seat full of children.
How to avoid petrol in a diesel on your next fill-up around Symonds Green
- A green handle for unleaded and black for diesel is usual in the UK — yet not on each forecourt. Trust the label on the pump, not the colour.
- The first fill in an unfamiliar car is the time to check your filler flap — on it, or on the cap, many motors state which fuel to use.
- A coloured fob or a sticker on the diesel's key achieves more than any amount of intending to remember, for a house with one of each.
- Say it before you lift it. On your first fill in a new or hired car, say "diesel" aloud before you take the nozzle off the petrol pump. It sounds daft and it works.
- Put the phone away. This is an easy mistake to make whilst you are thinking about something else.
- A misfuel inhibitor helps, up to a point. Some diesels come with a filler designed to reject a petrol nozzle, and add-on devices are available for vehicles without one. They are a backstop, not a reason to stop reading the pump.
- Stop the moment you realise. Less petrol inside that tank means a weaker mixture. It does not change what to do next, which is still not to crank it.
Petrol already in a diesel in Symonds Green? Begin here
Then, there's only a short order of things. Starting it is out, and so is turning on the ignition. If you are still at the forecourt — Costco or anywhere else — ask the staff to help you roll the vehicle away from the petrol pump. Then ring 0333 366 0103 and tell us what got in, about how much, and whether it's run.
AdBlue, not petrol? Then tell us. Corrosion and deposits, not lost protection, make it a separate issue — Symonds Green has a page just for it.
Why one petrol in a diesel task around Symonds Green costs more than another
The four scenarios above are four different jobs, so no single quote for this would be honest. Mostly, your cost shifts with which situation you're in. Two things come after that: the petrol that went in as a share of what your tank holds, then the spot the car is in and whether our van can get to it safely.
Three questions come first, before quoting, rather than after — what was put in, how much, has it run — and this is the reason. Those answers change a range into a straight figure.
About Symonds Green
Symonds Green is a suburban area in Hertfordshire, situated approximately 28 miles north of London and 12 miles southwest of St Albans. Symonds Green sits at an elevation of around 106 metres, near the neighbouring areas of Fishers Green, Old Town, and Todds Green. Symonds Green is characterized by its predominantly terraced housing stock, which reflects the typical residential architecture of the region.
Across Hertfordshire and around Symonds Green: fuel drain cover
Fishers Green, Old Town and Todds Green are among the spots around Symonds Green that the same vans work, answering petrol in diesel jobs across Symonds Green's SG postcode area. A forecourt, a supermarket car park, a lay-by or your own drive are all places our technicians drain, and the vehicle doesn't need to move to us.
Symonds Green: still at the petrol pump?
Nothing beats it: that's where you now are. Switched off it remains; then call.