How Worried Should You Be? Petrol in a Diesel Car in High Lane
Less than you likely are, if it has not been started. Everyone around High Lane starts with "have I ruined it?", and the fair answer is normally no: petrol resting in that tank of a diesel remains harmless until priming, cranking or driving draws it into the fuel system. Leave the engine off then ring Petrol in Diesel — that keeps it like that. 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.
Inside the motor: what petrol in a diesel does
On its way through an engine, diesel has two jobs. It lubricates first, and after that does it burn. Extremely fine clearances go into the fuel injectors and the high-pressure pump, and just your diesel running through keeps those surfaces from grinding together.
Poorly at the first, not at all at the second: that's petrol. A pump working on a petrol mix is wearing itself out, because petrol is runnier than diesel and takes away the protection the fuel system relies on. Petrol is also made to resist igniting under compression — the reverse of what a diesel wants from its fuel — and that's where the rattling starts.
The shape of the problem is plain when you put those together. Not contact but circulation is what does the harm. Petrol in the tank is a fuel problem. A pump that has been running on that petrol is the start of a mechanical one, and whatever a worn pump sheds moves on with your fuel to the fuel injectors further on.
Petrol in a diesel in High Lane: how serious is it? Four situations
Filled but not once started — the best it gets. The petrol is inside that tank and only that tank, and the task is a drain and a flush where the car stands. This is the one scenario that can only truly occur on a forecourt, as anywhere else your car has been driven to get there.
Your ignition switched on, or a brief start. Your system has been bled, and so petrol has left that tank and reached the filter and the fuel lines. Usually nothing more than clearing, purging and seeing to your filter, so still straightforward.
Driven a couple of miles. Now your pump has spent these miles running on weakened fuel. Distance is only half of that; how hard it was driven matters just as much. Either way the work includes the tank, the fuel lines, the filter and fresh fuel through the entire system. On the school run to High Lane Primary School, the miles is short. Very different again: a trip to Manchester, under 15 miles away, or any mileage on the M60, under 5 miles from High Lane, where the engine kept working hard.
Driven on till it complained — clattering, smoke, a lumpy idle, a soft throttle. That's the engine telling you its fuel no longer is acting like diesel. Leave it where it has stopped: a lay-by, a side street, the verge on Andrew Lane. The fuel drain and flush-through still come first, and they deal with it: if a vehicle is pulled over quickly, long-term damage is very unusual.
What High Lane motorists get told about petrol in a diesel — and the stories in it
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 mixture is all it gives, because topping up removes nothing. That guidance supposes a diesel fuel system handles petrol by percentage. It does not.
"Modern diesels can handle a little petrol" — a myth, and closer to the opposite. Lubrication matters more on newer diesels, not less, because their fuel runs through more precise parts at higher pressure.
"It starts, it drives, so there is no harm" — the myth that trips up most motorists than any other. Feed diesel to a petrol motor and it generally will not run, so the motorist stops — and the harm stops with them. Nothing looks to have happened when a diesel fed petrol fires up, ticks over and drives away, which it usually does; meanwhile your pump grinds. Being able to run is not proof of being fine.
An outdated workaround for a different problem is behind this one. Myth: "Add some two-stroke oil and drive it home." The petrol is still inside your tank afterwards, and what it has diluted is not put back.
If your engine has run, part of the petrol is in your filter and the fuel lines, not your tank — and the next start pulls it right back through your pump. So the myth "drain that tank yourself and you are sorted" does not stand up. Draining petrol into a can by the kerbside is also truly risky.
How it happens: petrol in a diesel
On purpose? Never. Through carelessness? Seldom, if ever. The petrol nozzle is the smaller of the two and slips into a diesel filler with almost no resistance; a diesel nozzle generally will not go into a petrol motor at all. The forecourt makes it easy, and the slip runs one way.
It takes place when habit and your car stop matching. A new motor, a hire car or a courtesy car. Households running one of each, petrol and diesel. A forecourt you know, only with its pumps laid out differently. A hurried fill en route to Middlewood with a train to catch. The first fill-up in a diesel BMW 3 Series after years of driving petrol is exactly the moment it takes place. Throw in a back seat full of children, a phone call or rain, and the hand wins.
Preventing petrol in a diesel next time you fill up in High Lane
- Not every forecourt in the UK keeps to green for unleaded and black for diesel, though most usually do. Read the petrol pump's label; the colour is just a clue.
- Plenty of motors state the fuel type inside the filler flap or on the cap, and so check there on your first fill in any car you do not know.
- One of each in the home? Mark the key to your diesel — a bright fob, a sticker — because meaning to remember isn't enough.
- Say it before you lift it. On the first fill in a new or hired car, say "diesel" aloud before you lift the nozzle off the petrol pump. It seems silly and it works.
- Put your phone away. This is an easy mistake to make while you're thinking about something else.
- Some diesels come with a filler built 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 backstop, not a reason to stop reading the pump.
- As soon as you realise, stop: less petrol inside your tank makes a weaker mix. What to do next doesn't change, though — still don't start the car.
Put petrol in a diesel around High Lane already?
Then the order of things is brief. Leave it unstarted, with your ignition switched off as well. Ask the staff to help you roll it clear of the petrol pump if you're still at the forecourt, whether that's BP or anywhere else. Call 0333 366 0103 next, with three answers — the fuel, the rough quantity, and if it's run.
Corrosion and deposits are the trouble with AdBlue, whereas petrol brings lost lubrication. So if it was AdBlue, say so — and read its own High Lane page.
One petrol in a diesel job in High Lane costs more than another. Why?
There is no honest single price for this, because the four situations above are four different tasks. What shifts the cost is mostly which of them you are in. Where the vehicle is matters too, and whether a van can safely get to it, after the share of petrol to what your tank takes.
What got in, how much, and if it's run — three questions we ask before pricing, not after, for exactly that reason. A range becomes a straight figure when the replies are in.
About High Lane itself
High Lane is a village in Greater Manchester, situated on the River Mersey at an elevation of 177 metres. High Lane has a mix of old and new housing, with detached homes being the predominant type, and is located near other small villages such as Windlehurst and Middlewood. High Lane is close to the city of Manchester, approximately 10.8 miles away, and is part of the wider North West region of England. High Lane has a population of around 2401 residents.
High Lane and Greater Manchester: where our fuel drain cover runs
The vans answering petrol in diesel jobs around High Lane, in the SK postcode area, equally work the locations around it, Windlehurst, Middlewood and Hawk Green included. The vehicle doesn't need to move to us: we drain on a forecourt, in a supermarket car park, in a lay-by or on your own drive.
Still at the pump in High Lane?
Then, you could not be in a better spot. Turned off it remains; then phone.