Petrol in a Diesel Car in Willowbank: How Worried Should You Be?
Less than you likely are, if it has not been started. "Have I ruined it?" is the first thing anyone in Willowbank asks, and the honest answer is usually no, since petrol resting in a diesel tank hurts nothing until it's drawn through the fuel system — by ignition priming, by the starter, or by driving. Keep it like that: leave your engine off and call Petrol in Diesel. The remainder of this page covers what petrol really does to a diesel, how to judge how far it has got, and how to make sure it does not happen to you again.
Petrol in a diesel: what does it do to the motor?
Diesel has two jobs on its way through an engine. It combusts, and before it combusts it lubricates. Your high-pressure pump and the injectors are made to extremely fine clearances, and your diesel passing through them is what keeps those surfaces from wearing against one another.
Badly at the first, not at all at the second: that's petrol. Being less viscous than diesel, petrol strips away the lubrication a fuel system needs, leaving a pump on the mixture to wear itself. It's equally made to resist igniting under compression — the reverse of what a diesel needs — which is where you hear the clattering.
The shape of the trouble is plain when you put those together. It is circulation that causes the harm, not contact. Petrol in the tank is a fuel problem. The beginning 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 injectors beyond it.
Petrol in a diesel around Willowbank: how bad is it? Four situations
The best case there is: filled up, not once started. Being on a forecourt is what makes this possible: elsewhere, your car has been driven there to begin with. With the petrol kept in that tank alone, it is cleared and flushed right where it stands, and nothing more is needed.
The ignition switched on, or a short start. Petrol has come out of that tank and reached the filter and the fuel lines, because the fuel system has been bled. Normally nothing more than clearing, cleaning and sorting the filter, so still easy.
A few miles driven, and the pump has spent each of them running on diluted fuel. The work is the tank, the lines, the fuel filter and fresh fuel through the whole circuit, and how hard the car was driven counts as much as how far. Short trips, such as the school run to the local primary school, are one thing. Very different a second time: a trip to Inverness, over 50 miles away, or any distance on the M90, over 50 miles from Willowbank, where your engine never stopped running hard.
Driven on until it protested — knocking, smoke, a lumpy idle, a soft throttle. The motor is telling you your fuel is no longer behaving like diesel. Pull up wherever you are — the verge on Leishman Avenue, a lay-by, a side street — then leave it there. The fuel drain and flush-through still go first, and they sort it out: when a car is stopped soon, permanent damage is very unusual.
Stories Willowbank drivers hear about petrol in a diesel
It will not be fine. The myth: "Fill it the rest of the way with diesel and it will be." A bigger tank of the same mix is all it gives, because topping up takes out nothing. That advice presumes a diesel fuel system tolerates petrol by percentage. It does not.
Myth: "A modern diesel can cope with a bit of petrol." If anything, the opposite. At higher pressure, through finer parts: that is how a modern diesel handles its fuel, so the protection matters more, not less.
Myth: "If it starts and drives, there's no damage done." This is the one that catches drivers. Any petrol engine fed diesel generally won't run, so the motorist stops and the harm stops with them. Feed petrol to a diesel and it usually starts, ticks over and drives away as if nothing has happened — all the while its pump is wearing. Being able to run isn't proof of being fine.
Not so: a two-stroke additive makes it safe to drive home. It was an old workaround, meant for another problem. The petrol is still in the tank afterwards, and what it has thinned isn't put back.
"Drain it yourself and you are sorted" — a myth, since after it's been running some petrol lies in the filter and lines, waiting to go right back through the pump on the next start. It is also truly risky to drain petrol into a can at the kerbside.
Why petrol in a diesel takes place at all
It's seldom carelessness, and nobody does it on purpose. A diesel nozzle mostly will not fit a petrol car, but the narrower petrol nozzle goes into the filler of a diesel almost without resistance — so forecourts make this one mistake straightforward, and just in that direction.
Habit and the car getting out of step is when it occurs. A new car, a hire car or a courtesy car. A household with one petrol and one diesel on the drive. The pumps in a different order on a familiar forecourt. Filling up in a rush en route to Wick, with a train to catch. The first fill-up in a diesel Volkswagen Golf after years of driving petrol is precisely the moment it occurs. Add a back seat full of children, a phone call or rain, and habit wins.
How to avoid petrol in a diesel on your next fill-up in Willowbank
- The label is what matters, so read the petrol pump rather than the colour: in the UK unleaded handles are normally green and diesel black, but not on each forecourt.
- Many cars state the fuel inside the filler flap or on the cap, and so check there on the first fill in a car you do not know.
- Good intentions do less than a sticker or a fob in a bright colour on the diesel's key when a household has one of each. So mark it.
- Say it before you lift it. On the first fill in a new or hired car, say "diesel" out loud before you lift the nozzle off the petrol pump. It seems daft and it works.
- Tuck the phone away. This is an easy mistake to make while you're thinking about something else.
- A misfuel inhibitor helps, up to a point. Some diesels have a filler built to refuse a petrol nozzle, and add-on devices are available for vehicles without one. They are a safety net, not a reason to stop checking the pump.
- Stop as soon as you notice. Less petrol inside the tank means a thinner blend. It doesn't change what to do next, which is still not to start it.
Already put petrol in a diesel around Willowbank?
Then the order of things is brief. Never start the vehicle, and do not switch the ignition on. Ask the staff to help you roll it clear of the petrol pump if you are still at the forecourt, whether that is JET or anywhere else. What got in, about how much, and whether it's run: tell us that when you phone 0333 366 0103.
AdBlue, not petrol? Then tell us. Corrosion and deposits, not lost lubrication, make it a separate problem — Willowbank has a page all for it.
One petrol in a diesel task in Willowbank costs more than another. Why?
A fair single quote does not exist here: four situations, four separate jobs. Chiefly, your cost moves with which situation you're in. After that it's the ratio — how much petrol got in against how much your tank takes — and after that where your car is and whether our van can reach it safely.
Three questions come first, before any quote, instead of after — what got in, how much, has it run — and that is the reason. Given the replies, you get a straight figure instead of a range.
About Willowbank and its setting
Willowbank is a coastal suburban area in the Highland county of Scotland, situated at an elevation of 25 metres. Willowbank lies near the towns of Wick and Broadhaven, and is also close to the village of Papigoe. Willowbank has a population of approximately 2375 people, predominantly living in semi-detached housing. Willowbank is located 78.7 miles from Inverness, the nearest city.
Fuel drain cover in Willowbank and across Highland
Petrol in diesel call-outs in Willowbank — part of the KW postcode area — go to vans that likewise cover the locations round it, Wick, Broadhaven and Papigoe included. A forecourt, a supermarket car park, a lay-by or your own driveway are all locations our technicians work, and your car doesn't need to come to us.
Still at the pump around Willowbank?
Nothing beats it: that's where you are. Call, and leave it turned off.