How Worried Should You Be? Petrol in a Diesel Car in Pool Hey
Not started? Then less worried than you likely are. Till the ignition primes your pump, the starter turns, or the vehicle is driven, petrol in a diesel tank simply waits there and does nothing. Which means the truthful reply to that first Pool Hey question — "have I wrecked it?" — usually no. Keep it that way: leave the motor off then phone Petrol in Diesel. 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.
What petrol in a diesel does to your engine
On its way through a motor, diesel has two jobs. It ignites, and before it combusts it protects. Built to very fine clearances, your injectors and the pump depend on your diesel flowing through them to stop their surfaces wearing against one another.
Of those two tasks, petrol handles the first poorly and the second not at all. It's runnier than diesel and takes away the lubrication the 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.
Seen together, they make clear what shape the issue has. It's movement that does the damage, not contact. All a tank with petrol in it amounts to is a fuel fault. A pump that has been labouring on that petrol is the beginning of a mechanical one, and whatever a worn pump sheds travels on with the fuel to the injectors downstream.
Four scenarios our engineers see in Pool Hey: how bad is petrol in a diesel?
Fuelled but never started — as good as it gets. Only your tank has petrol in it, so the job is draining that tank and purging the system where the car sits. This scenario can only really happen on a forecourt: anywhere else, the vehicle got there by being driven.
Ignition on, or started for a second. The system has been primed, so petrol has left the tank and reached your filter and your lines. Usually little more than clearing, flushing and seeing to the filter, and so still straightforward.
Driven a couple of miles. Now the pump has spent these miles running on weakened fuel. Tank, lines, filter, then fresh fuel put through the whole circuit: that is this work, and the way your car was driven matters as much as the miles. Short trips, such as the school run to Kew Woods Primary School, are one matter. A run as far as Preston, under 15 miles away, is a very different task. So is any distance on the M58, under 10 miles from Pool Hey, where the motor has been labouring hard throughout.
It complained, and only then stopped: smoke, clattering, a throttle gone soft, an idle gone lumpy. The fuel isn't behaving like diesel any more, and the engine is saying so. Stop wherever you are — the verge on Pool Hey Lane, a lay-by, a side street — then leave the car where it is. A vehicle stopped quickly very rarely has lasting damage, because the fuel drain and the flush-through, which still go first, sort it out.
What Pool Hey motorists get told about petrol in a diesel — and the stories in it
False: topping up to full with diesel makes it fine. It does not. Nothing is removed by topping up — you are left with a fuller tank, still the same mix. Percentage is not how a diesel fuel system tolerates petrol, whatever that advice assumes.
Not so: a newer diesel copes with a bit of petrol. Rather, the opposite. A modern diesel runs its fuel through more precise parts at higher pressure, which makes the lubrication count more, not less.
Myth: "If it starts and drives, there's no harm done." This is the one that catches drivers. The motorist of a petrol motor fed diesel usually 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, as it usually will; meanwhile the pump grinds. A running engine does not mean fine.
An old fix for a different issue lies behind this one. Myth: "Add some two-stroke oil and drive it home." None of what petrol weakened gets put back by it — and later, the tank still contains the petrol.
The next start sends petrol back round your pump from your lines and your filter, where some of it ends up once the engine has been run. That is why a DIY tank drain does not sort it — a myth. Besides, petrol cleared into a can by the road is truly risky.
Why petrol in a diesel takes place at all
On purpose? Never. Through carelessness? Rarely, if ever. The petrol nozzle is the smaller of the two and slips into a diesel filler with almost no resistance; a diesel nozzle mostly won't go into a petrol motor at all. The forecourt makes it simple, and the error runs one way.
Routine and the car getting out of step is how it happens. Any car that is new to you — hired, on loan as a courtesy car, or brand new. 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 on the way to Meols Cop. Exactly the moment it takes place: after years of driving petrol, someone fills a diesel Volkswagen Golf for the first time. With rain, a call coming in, or children to deal with, the hand just does what it has always done.
How to avoid petrol in a diesel at your next fill-up in Pool Hey
- The label is what counts, so read the pump rather than the colour: in the UK unleaded handles are normally green and diesel black, yet not on every forecourt.
- The first fill in a new vehicle is the time to check your filler flap — on it, or on the cap, many cars state the fuel to use.
- One of each in the home? Mark your key to your diesel — a coloured fob, a sticker — because meaning to remember isn't enough.
- Before the nozzle leaves the petrol pump the first time you fill a hired or new car, say "diesel" out loud. Daft, perhaps, but it works.
- Tuck your phone away. This is an easy mistake to make whilst you are thinking about something else.
- Up to a point, a misfuel inhibitor helps: some diesels have a filler built to refuse a petrol nozzle, and add-on devices are available for the remainder. Count it as a safety net, and keep checking the petrol pump.
- As soon as you notice, stop: less petrol in that tank means a thinner mixture. What to do next does not change, though — still don't start the vehicle.
Pool Hey: already put petrol in a diesel?
In that case, there is only a short order of things. Leave it unstarted, with the ignition switched off too. The attendants at the forecourt — whether at Tesco itself or wherever you filled up — will usually help push it clear of the pump if you ask. Next, 0333 366 0103. We will ask what got in, about how much, and if it's been run.
AdBlue, not petrol? Then tell us. Corrosion and deposits, not lost lubrication, make it a separate fault — Pool Hey has a page just for it.
What makes one Pool Hey petrol in a diesel task cost more than the next
Four separate tasks lie behind the four situations above — which is why there is no honest single price. Which of them you are in is chiefly what moves your cost. After that it's the ratio — how much petrol went in against how much the tank holds — and after that where the vehicle is and whether a van can reach it safely.
What got in, how much, and whether it has run — three questions our technicians ask before quoting, not after, for exactly that reason. A range becomes a straight figure once those replies are in.
About Pool Hey itself
Pool Hey is a small coastal suburban area in Lancashire, situated near the cities of Preston and Southport. Pool Hey sits at a low elevation of around 4 metres, close to the shoreline of the Irish Sea. Pool Hey is characterised by its predominantly detached housing stock, with nearby places including Brown Edge, Carr Cross, and Jacks Mere.
Fuel drain cover around Pool Hey and across Lancashire
Petrol in diesel call-outs in Pool Hey — part of the PR postcode area — go to teams that also cover the locations round it, Brown Edge, Carr Cross and Jacks Mere among them. You need not move your car to us. Forecourts, supermarket car parks, lay-bys and your own drive are all spots where we work.
Still at the petrol pump in Pool Hey?
No position is better: that's where you are. Keep it off. Ring.