Brediland: Petrol in a Diesel Car? How Worried to Be
Likely less than you already are — provided no one has started the car. Petrol resting in a diesel tank does nothing to your motor till something pulls it through the system — the ignition priming your pump, your starter, or the drive on its own. So the honest answer to the first query everyone in Brediland asks, "have I wrecked it?", is normally no. Leave the motor off then call Petrol in Diesel — that is how you keep it that way. The remainder of this page sets out what petrol actually does to a diesel, how to tell how far it has got, and how to make sure it doesn't happen to you again.
Petrol in a diesel: what does it do to the engine?
On its way through a motor, diesel does two tasks. It protects first, and only then does it burn. What stops the surfaces inside the high-pressure fuel pump and your injectors from wearing down against one another is your diesel flowing through them — they're designed to extremely fine tolerances.
Petrol handles the first task badly and the second not at all. It's runnier than diesel and removes the protection the system rests on, and so a pump running on a petrol mixture is a pump wearing itself. And petrol is designed to resist igniting under compression, which is the reverse of what a diesel needs from its fuel. That is where the knocking comes from.
Seen together, they show the shape the issue has. Not contact but circulation is what causes the damage. A tank with petrol in it is a fuel issue. After your pump has been working on that petrol, a mechanical fault has begun: anything shed by a pump that is grinding travels downstream to the injectors with your fuel.
How bad is petrol in a diesel? Four situations our technicians see in Brediland
Filled but not once started — the best it gets. Being at a forecourt is what makes this the case: elsewhere, the vehicle has been driven there to begin with. With that petrol kept in that tank alone, it is emptied and flushed right where it stands, and nothing more is needed.
Your ignition turned on, or a short start. With the fuel system primed, your lines and filter already hold petrol that has come from the tank. Still generally straightforward: drain, flush, and the fuel filter dealt with.
Driven a couple of miles. Now the pump has spent these miles running on weakened fuel. The work is the tank, the lines, the filter and clean fuel through the whole system, and how hard your car was driven counts as much as how far. Driving the kids to the local primary school is one sort of trip. A run as far as Glasgow, under 10 miles away, is a very different task. So is any mileage on the M8, under 3 miles from Brediland, where the motor has been running hard throughout.
Driven on till it complained — knocking, smoke, a ragged idle, a soft throttle. The fuel isn't behaving like diesel any more, and your engine is saying so. Stop wherever you are — the verge on Garry Drive, a lay-by, a side street — then leave the vehicle there. Long-term damage is very uncommon if a car is stopped soon, and the fuel drain and flush that still go first take care of it.
What Brediland people get told about petrol in a diesel — and the stories in it
Myth: "Fill it the rest of the way with diesel and it will be fine." It will not. Topping up removes nothing; it gives you a fuller tank of the same mix. Percentage isn't how a diesel fuel system tolerates petrol, whatever that guidance presumes.
Myth: a modern diesel copes with a bit of petrol. If anything, the opposite. Finer components and higher pressure are how a newer diesel runs its fuel, and that makes the protection matter more, not less.
This is the one that fools motorists. Myth: "If it starts and drives, there's no harm done." The motorist of a petrol engine fed diesel usually has no choice but to stop, since it will not run, and the harm stops with them. Nothing looks to have happened when a diesel fed petrol fires up, ticks over and drives away, as it usually does; meanwhile your pump wears. Fine and running aren't the same thing.
An old workaround for a separate fault lies behind this one. Myth: "Add some two-stroke oil and drive it home." The petrol is still in that tank afterwards, and whatever it has thinned isn't put back.
The next start draws petrol back round the pump out of the lines and the filter, where some of it sits after your engine has run. That's why a DIY tank drain doesn't sort it — a myth. And, a can of petrol drained by the kerbside is truly risky.
How does petrol in a diesel take place?
It is rarely carelessness, and no one does it on purpose. One way only, since of the nozzles: the narrower petrol one slips inside a diesel filler with almost no resistance, whereas the diesel one mostly will not fit a petrol car. That's how the forecourt makes it simple.
The moment routine stops matching your car is the moment it happens. Hire cars, courtesy cars, and cars that are new to you. A household with one petrol and one diesel on the drive. The pumps in a different order on a well-known forecourt. Rushing for a train at Paisley Canal and filling up en route. A new-to-you diesel Volkswagen Golf, its first fuelling, and a driver used to petrol: exactly when it happens. Throw in a back seat full of children, a phone call or rain, and habit wins.
Next time you fill up in Brediland: avoiding petrol in a diesel
- Not every forecourt in the UK follows green for unleaded and black for diesel, even if most usually do. Check the pump's label; the colour is only a hint.
- The first fill in a strange vehicle is the time to check the filler flap — inside it, or on the cap, many cars state which fuel they take.
- A coloured fob or a sticker on the diesel's key does more than any amount of intending to remember, for a household with one of each.
- Before the nozzle leaves the petrol pump the first time you fuel a hired or new vehicle, say "diesel" aloud. Daft, perhaps, but it does the trick.
- Whilst you're thinking about something else, this is an easy mistake to make — so put the phone away.
- Up to a point, a misfuel inhibitor helps: some diesels come with a filler built to block a petrol nozzle, and aftermarket devices exist for the remainder. Treat it as a backstop, then keep reading the pump.
- Stop the moment you notice. Less petrol in the tank makes a thinner blend. It doesn't change what to do next, which is still not to fire it up.
Already put petrol in a diesel in Brediland?
The order of things is brief, then. Don't turn the ignition on, and do not crank it. Ask the attendants to help you roll it away from the pump if you're still at the forecourt, whether that's JET or somewhere else. Next, 0333 366 0103. We will ask what was put in, roughly how much, and if it has been run.
Corrosion and deposits are the issue with AdBlue, where petrol means lost lubrication. So if it was AdBlue, say so — and read its own Brediland page.
Why one petrol in a diesel job around Brediland costs more than another
There's no fair single quote for this, since the four situations above are four separate tasks. Which of them you are in is mostly what moves the cost. The proportion counts next, meaning how much of that tank is petrol, followed by the location of your car and whether reaching it is safe for a van.
What got in, how much, and if it's run — three queries our technicians ask before costing, not after, for precisely that reason. Those replies change a range into a straight figure.
About Brediland
Brediland is a suburban area situated on the lakeside in Renfrewshire, with a relatively low elevation of 33 metres. Brediland lies close to Glasgow, Scotland's largest city, and is part of the wider Glasgow urban area. Brediland is characterised by its predominant housing type, which is mainly flat, and is near other suburban areas such as Lounsdale and Meikleriggs.
Brediland and Renfrewshire: where our fuel drain cover reaches
Brediland sits in the PA postcode area, and our teams that answer petrol in diesel calls there work the places near it as well — Lounsdale, Stanely and Meikleriggs among them. No need to move the car to us. Forecourts, supermarket car parks, lay-bys and your own driveway are all spots where we work.
Still at the petrol pump in Brediland?
Then you are in the best position there can be. Keep it off. Call.