Top of Moor: Petrol in a Diesel Car? How Worried to Be
Less than you likely are, provided it hasn't been started. "Have I wrecked it?" is the first question anyone around Top of Moor asks, and the honest answer is generally no, because petrol resting in a diesel tank hurts nothing until it is drawn through the system — by ignition priming, by your starter, or by being driven. Keep it like that: leave your motor off then call Petrol in Diesel. Further down, this page sets out what petrol actually does inside a diesel, how far it may have gone, and how to stop it happening to you a second time.
What petrol in a diesel does to the motor
On its way through an engine, diesel has two jobs. Before it ignites, it protects — and then it combusts. Designed to extremely fine gaps, the fuel injectors and the pump depend on the diesel flowing through them to keep their surfaces from wearing against one another.
The second task petrol doesn't do at all, and the first it does badly. Being less viscous than diesel, petrol strips out the protection a fuel system needs, leaving a pump on that mixture to wear itself. It is equally made to resist igniting under compression — the opposite of what a diesel needs — which is where you get the rattling.
The shape of the trouble is clear once you put those together. It's movement that causes 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 fuel injectors downstream.
Four scenarios our engineers see around Top of Moor: how serious is petrol in a diesel?
Filled up, and never started: nothing beats it. Being on a forecourt is what makes this the case: elsewhere, the car has been driven there to begin with. With that petrol kept inside your tank alone, it is emptied and rinsed on the spot, and nothing more is needed.
A brief spell of running, or merely the ignition on. Your system has been bled, so petrol has left the tank and reached the filter and the fuel lines. Still generally easy: drain, flush, and the fuel filter sorted.
Those few miles on the road meant the pump labouring on fuel diluted by petrol throughout. Mileage is only half of that; how hard it was driven counts equally. Either way the work runs to the tank, the fuel lines, your filter and clean fuel through the entire system. On the school run to Littlemoor Primary School, the distance is small. Very different again: a run to Manchester, under 10 miles away, or some mileage on the A627(M), under 3 miles from Top of Moor, where your engine never stopped labouring hard.
Knocking, an uneven idle, smoke, a throttle gone soft: driven until it complained. The fuel is not behaving like diesel any more, and the engine is telling you. Whether it is the verge on Walnut Avenue, a lay-by or a side street, stop where you are then leave it. What goes first is still the fuel drain and flush-through, and that sorts it out, with lasting damage very rare when a car is stopped quickly.
What Top of Moor 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'll be fine." It will not. Topping up takes out nothing; it gives you a fuller tank of the same mixture. Percentage isn't how a diesel fuel system copes with petrol, whatever that advice assumes.
If anything, the reverse holds. Myth: "A current diesel can cope with a bit of petrol." Protection counts more on modern diesels, not less, since their fuel passes through finer parts at higher pressure.
This is the one that catches drivers. Myth: "If it starts and drives, there's no damage done." Feed diesel to a petrol engine and it generally won't run, so the motorist stops — and the harm stops with them. A diesel fed petrol usually starts, idles and drives away as though nothing has happened, whilst the pump wears. Being able to run isn't the same as being fine.
Myth: a two-stroke additive lets you to drive home. It was an old workaround, meant for another issue. That petrol is still inside the tank after that, and what it has weakened is not put back.
Myth: "Drain that tank yourself and you are sorted." Once the motor has been run, some of that petrol is no longer inside your tank: it's in your filter and the fuel lines, and it goes straight back through your pump at your next start. Clearing petrol into a can at the kerbside is also really risky.
How it happens: petrol in a diesel
No one does it on purpose, and it is seldom carelessness. The petrol nozzle is the slimmer of the two and slips into a diesel filler with almost no resistance; a diesel nozzle generally will not go into a petrol vehicle at all. The forecourt makes it simple, and the mistake runs one way.
When habit and your car stop matching, it happens. A new vehicle, a hire car or a courtesy car. One petrol and one diesel on the driveway of the same household. The pumps in a different order on a familiar forecourt. Rushing for a train outside Mossley (Manchester) and filling up en route. Years of petrol motors behind you, a diesel Renault Megane in front of you at the forecourt for its first tank — that is when. Add a back seat full of kids, a phone call or rain, and the hand wins.
Next time you fill up in Top of Moor: avoiding petrol in a diesel
- Not every forecourt in the UK keeps to green for unleaded and black for diesel, though most generally do. Read the pump's label; the colour is just a clue.
- In a car you don't know, look inside the flap over the filler or at the cap before your first fill: many vehicles print the fuel there.
- Label your key. In a house with one of each, a coloured fob or a sticker on the diesel's key does more than any amount of meaning to remember.
- "Diesel", out loud, before you pick up the nozzle — every time a new or hired car gets its first tank. It seems silly. It does the trick.
- Thinking about something else is when this becomes an easy mistake to make, so tuck the phone away then keep your mind on the petrol pump.
- A misfuel inhibitor helps, up to a point. Some diesels come with a filler built to block a petrol nozzle, and add-on devices are available for motors without one. They are a safety net, not a reason to stop reading the pump.
- Stop the moment you notice. Less petrol in that tank makes a weaker blend. It doesn't change what to do next, which is still not to start it.
Already put petrol in a diesel around Top of Moor?
The order of things is brief, then. Don't switch your ignition on, and don't start it. If you are still on the forecourt — Shell or anywhere else — ask the attendants to help you push the vehicle away from the petrol pump. Then call 0333 366 0103 and tell us what was put in, about how much, and whether it has run.
Corrosion and deposits are the issue with AdBlue, where petrol brings lost lubrication. So if it was AdBlue, say so — and read its own Top of Moor page.
Why one petrol in a diesel job in Top of Moor costs more than another
The four scenarios above are four different tasks, so no single quote for this would be fair. Which of them you're in is mostly what moves your cost. Two things follow that: the petrol that got in as a proportion of what the tank holds, then the spot the car is in and whether our van can reach it safely.
Three questions come first, before any quote, rather than after — what went in, how much, has it run — and this is the reason. With those replies, you get a straight figure instead of a range.
About Top of Moor and where it is
Top of Moor is a suburban area situated near the River Mersey in Greater Manchester, with a mix of terraced housing and local amenities. Top of Moor sits at an elevation of 237 metres, overlooking the surrounding landscape and providing views of the nearby countryside. Top of Moor is located close to several nearby places, including Greenacres Fold, Greenacres, and Spring Hill, and is approximately 8 miles from Manchester city centre.
Across Greater Manchester and around Top of Moor: fuel drain cover
Petrol in diesel jobs around Top of Moor — part of the OL postcode area — go to vans that likewise cover the places round it, Greenacres Fold, Greenacres and Spring Hill among them. You need not move the vehicle to us. Forecourts, supermarket car parks, lay-bys and your own drive are all places where we work.
Still at the petrol pump around Top of Moor?
In that case, you couldn't be in a better place. Turned off it stays; then phone.