Exmouth: Petrol in a Diesel Car? How Worried to Be
Less than you likely are, provided it has not been started. "Have I wrecked it?" is the first thing anyone around Exmouth asks, and the truthful answer is normally no, because petrol left in a diesel tank harms nothing until it's drawn through the fuel system — by ignition priming, by your starter, or by driving. Petrol in Diesel is who to phone, with the engine kept off, so it stays that way. Read on for three things: the effect petrol has inside a diesel engine, the clues of how far it has spread, and ways to make sure you never do it again.
Petrol in a diesel: what does it do to the engine?
Diesel does two jobs on its way through an engine. Oiling comes before burning; it does both. Built to extremely fine gaps, your injectors and the pump depend on the diesel flowing through them to stop their surfaces wearing against one another.
Of those two jobs, petrol manages the first badly and the second never. A pump running on a petrol blend is wearing itself out, since petrol is runnier than diesel and strips out the protection your fuel system depends on. Petrol is also made to resist igniting under compression — the reverse of what a diesel wants from its fuel — and that is where the rattling comes.
Put those together and the shape of the trouble is plain. Not contact but circulation is what causes the damage. A tank with petrol in it is a fuel issue. The start of a mechanical one is a pump that has been running on that petrol — and whatever a worn pump sheds travels on with the fuel to the fuel injectors downstream.
Four situations our technicians see around Exmouth: how bad is petrol in a diesel?
Filled up, never started. The best case there is. On a forecourt, and truly only there, that petrol is still confined to that tank — because anywhere else your car was driven to get to it. The task is emptying and rinsing on the spot.
A moment's running, or just the ignition on. Once primed, your system has drawn petrol from that tank as far as the fuel filter and the lines. Still usually straightforward: drain, flush, and the filter seen to.
Driven a couple of miles. Now the pump has spent these miles running on diluted fuel. How hard your car was driven counts as much as how far, and the work takes in the tank, your lines, your filter and fresh fuel through the entire system. A school run to The Beacon Church of England (VA) Primary School is one thing. A run as far as Exeter, under 10 miles away, is a very different job. So is any mileage on the M5, under 10 miles from Exmouth, where your engine has been running hard the whole time.
Driven on till it protested — clattering, smoke, an uneven idle, a dead throttle. The motor is telling you your fuel is no longer behaving like diesel. Whether it's the verge on Church Street, a lay-by or a side street, stop where you are then leave it. Long-term damage is very rare if a car is pulled over early, and the fuel drain and flush-through that still come first sort it out.
Exmouth people and that petrol in a diesel myths they hear
Myth: "Fill it the rest of the way with diesel and it will be fine." It will not. Nothing is removed by topping up — you're left with a fuller tank, still the same mix. The assumption behind that guidance — that diesel fuel systems tolerate petrol by percentage — is wrong.
If anything, the reverse is true. Myth: "A modern diesel can cope with a bit of petrol." A newer diesel sends its fuel through smaller components at higher pressure, which makes the protection count more, not less.
"It starts, it drives, and so no harm done" — the myth that trips up more motorists than any other. The driver of a petrol engine fed diesel normally 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.
Myth: a two-stroke additive lets you to drive home. It is an old workaround, supposed for another issue. What petrol has thinned stays diluted, and the petrol remains in the tank anyway.
The next start sends petrol back round your pump from the fuel lines and the fuel filter, where some of it sits once the engine has been run. That is why draining your tank yourself doesn't sort it — a myth. Clearing petrol into a can at the kerbside is also truly hazardous.
Why petrol in a diesel happens at all
No one does it on purpose, and it is rarely carelessness. The petrol nozzle is the slimmer of the two and slides into a diesel filler with almost no resistance; a diesel nozzle mostly won't go into a petrol car at all. The forecourt makes it easy, and the error runs one way.
When habit and the car stop matching, it happens. A car that is new to you — a hire car, on loan as a courtesy car, or just bought. One petrol and one diesel on the driveway of the same household. Your ordinary forecourt, its pumps now in a different order. Racing for a train outside the nearest station and filling up en route. Precisely the moment it occurs: after years of driving petrol, a driver fills a diesel Volkswagen Golf for the first time. Throw in 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 Exmouth
- Not every forecourt in the UK follows green for unleaded and black for diesel, though most generally do. Check the petrol pump's label; the colour is just a clue.
- Plenty of cars 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.
- Label the key. In a household with one of each, a coloured fob or a sticker on your diesel's key does more than any amount of intending to remember.
- "Diesel", aloud, before you pick up the nozzle — every time a new or hired car needs its first tank. It seems daft. It does the trick.
- Mistakes like this are simple to make while your mind is on something else, and so your phone goes away.
- Some diesels come with a filler designed to reject a petrol nozzle, and devices you can add exist for cars without one. Such an inhibitor helps up to a point — as a safety net, not a reason to stop reading the pump.
- Less petrol makes a weaker mix, and so stop the moment you notice — while remembering that your next step is unchanged. It's still not to fire it up.
Put petrol in a diesel in Exmouth already?
Short and simple, then, is the order of things. Leave it unstarted, with your ignition off too. The attendants at the forecourt — whether at Shell itself or wherever you filled up — will usually help roll it away from the pump if you ask. Next, 0333 366 0103. We'll ask what got in, about how much, and if it's been run.
If it was AdBlue and not petrol, say so. That's a separate problem — corrosion and deposits and not lost protection — and it has its own page for Exmouth.
What makes one Exmouth petrol in a diesel job cost more than the next
Four separate tasks lie behind the four situations above — which is why there's no fair single quote. Which of them you're in is mostly what moves your cost. The ratio matters next, meaning how much of your tank is petrol, followed by the position of the car and whether reaching it is safe for a van.
That's why our engineers ask three queries before pricing rather than after: what went in, how much, and whether it has run. Those replies turn a range into a straight figure.
About Exmouth
Exmouth is a coastal town in Devon, situated on the east bank of the Exe Estuary, with The Point and Withycombe Raleigh to the south and Hulham to the north. Exmouth has a population of approximately 15072 people and is characterized by predominantly terraced housing. Exmouth is located near the city of Exeter, about 8.9 miles away, and is a notable settlement in the South West region. Exmouth sits at a low elevation of around 9 metres above sea level, close to the sea.
Fuel drain cover across Devon, Exmouth included
Exmouth waits in the EX postcode area, and our vans that answer petrol in diesel call-outs there work the locations around it as well — The Point, Withycombe Raleigh and Hulham among them. Our engineers drain where your car is — your own drive, a lay-by, a supermarket car park, a forecourt — so it never needs to come to us.
Still at the petrol pump in Exmouth?
The best place there is, then — that's where you are. Switched off it remains; then ring.