Aintree: Petrol in a Diesel Car? How Worried to Be
Provided it hasn't been started, you can worry far less than you probably are. "Have I wrecked it?" is the first thing anyone around Aintree asks, and the truthful answer is generally no, because petrol resting in a diesel tank hurts nothing till it is drawn through the fuel system — by ignition priming, by your starter, or by being driven. Leave your engine off then call Petrol in Diesel — that keeps it like that. The remainder of this page explains what petrol really does to a diesel, how to tell how far it has got, and how to make sure it does not happen to you a second time.
Petrol in a diesel: what does it do to the engine?
Passing through a motor, diesel is doing two jobs at the same time. Before it ignites, it lubricates — then it combusts. Designed to very fine gaps, the fuel injectors and your pump rely on the diesel flowing through them to stop their surfaces wearing against one another.
The second task petrol doesn't do at all, and the first it does poorly. The clattering comes from petrol being designed not to ignite when compressed, which is precisely the reverse of what a diesel needs. On top of that it is thinner than diesel, it strips away the lubrication your system depends on, and any pump working on such a mixture is wearing itself.
Put these together and the shape of the trouble is clear. The harm is done by circulation, not by contact. Petrol in a tank is a fuel problem. Whatever a worn pump sheds travels on, borne by the fuel, into your injectors downstream, which is why a pump that has been working on that petrol is where a mechanical issue starts.
Four scenarios our engineers see around Aintree: how bad is petrol in a diesel?
Fuelled up, not once started. The best case there can be. Just the tank has petrol in it, and so the task is emptying the tank and rinsing the system where the vehicle stands. This scenario can only truly happen on a forecourt: anywhere else, your car got there by being driven.
Started for a second, or only the ignition on. With your system primed, the lines and filter already contain petrol that came from your tank. Drain, flush, see to your filter: still usually easy.
Those few miles on the road were your pump running on fuel weakened by petrol the whole way. How hard the vehicle was driven matters as much as how far, and the work takes in that tank, the fuel lines, the filter and fresh fuel through the entire system. Short trips, such as the school run to Holy Rosary Catholic Primary School, are one thing. Driving as far as Liverpool, under 10 miles away, makes a very different task — as does any mileage on the M57, under a mile from Aintree, with the motor labouring hard the whole time.
Driven until it protested. Knocking, a ragged idle, smoke, a throttle that has gone soft. The motor is telling you your fuel is no longer behaving like diesel. Leave it where it stops: a lay-by, a side street, the verge on Haileybury Avenue. Permanent damage is very unusual when a car is pulled over quickly, and the drain and flush-through that still come first deal with it.
Aintree motorists and that petrol in a diesel stories they hear
False: topping up to full with diesel makes it fine. It doesn't. Topping up takes out nothing; it gives you a bigger tank of the same mixture. That guidance assumes a diesel fuel system tolerates petrol by percentage. It does not.
Not so: a modern diesel copes with a bit of petrol. Rather, the reverse. More precise components and higher pressure are how a modern diesel runs its fuel, and that makes the lubrication matter more, not less.
This is the one that catches people. Myth: "If it starts and drives, there's no harm done." Feed diesel to a petrol motor and it usually won't run, and so the motorist stops — and the damage 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 the pump grinds. A running engine doesn't mean fine.
Not so: a two-stroke additive makes it safe to drive home. It was an old fix, meant for another fault. None of what petrol thinned gets put back by it — and later, that tank still holds the petrol.
Myth: "Drain your tank yourself and you are sorted." Once your engine has run, some of that petrol is no longer in that tank: it's in your filter and the lines, and it goes straight back through the pump at the next start. It is also genuinely hazardous to drain petrol into a can by the kerbside.
Petrol in a diesel: how does it occur?
On purpose? Never. Through carelessness? Seldom, if ever. The petrol nozzle is the slimmer of the two and slides into a diesel filler with almost no resistance; a diesel nozzle generally won't go into a petrol vehicle at all. The forecourt makes it easy, and the mistake runs one way.
It occurs when routine and the car stop matching. Hire cars, courtesy cars, and vehicles that are new to you. A household with one petrol and one diesel on the drive. Your normal forecourt, its pumps suddenly in a different order. A rushed fill en route to Old Roan with a train to catch. Years of petrol cars behind you, a diesel Volkswagen Golf in front of you on the forecourt for its first tank — that is when. Add rain, a phone call or a back seat full of children, and the hand repeats what it has always done.
Aintree drivers: how to avoid petrol in a diesel next time
- Green for unleaded and black for diesel is usual in the UK — yet not on every forecourt. Go by the label on the pump, not the colour.
- Many cars state the fuel type inside your filler flap or on the cap, and so check it on the first fill in a motor you do not know.
- One of each in the household? Label the key to your diesel — a bright fob, a sticker — since intending to remember is not enough.
- "Diesel", out loud, before you pick up the nozzle — each time a new or hired car gets its first tank. It sounds daft. It works.
- Mistakes like this are easy to make whilst your mind is on something else, and so your phone goes away.
- Add-on devices are available for cars without one, and some diesels are built with a filler that won't accept a petrol nozzle. Useful — but a backstop only, never a reason to stop checking the label.
- Spotting it mid-fill? Stop at once. A thinner mix results from less petrol in your tank, yet your next step stays the same: don't crank it.
Petrol already in a diesel in Aintree? Begin here
Then the order of things is brief. Leave it unstarted, with the ignition off too. Ask the staff to help you roll it clear of the petrol pump if you are still at the forecourt, whether that's Asda or anywhere else. Phone 0333 366 0103 next, with three facts — the fuel, the rough volume, and whether it's run.
Corrosion and deposits form the issue with AdBlue, where petrol brings lost protection. So if it was AdBlue, say so — and see its own Aintree page.
One petrol in a diesel job in Aintree costs more than another. Why?
Four different jobs lie behind the four scenarios above — which is why there's no fair single quote. What shifts the cost is mostly which of them you are in. Two things come after that: the petrol that was put in as a share of what that tank holds, then the spot the car is in and whether a technician can get to it safely.
Three queries come first, before quoting, rather than after — what went in, how much, has it run — and that is the reason. Their replies are what turn a range into one firm number.
About Aintree
Aintree is a village in Merseyside, situated on the riverside near Liverpool, with a mix of semi-detached housing and other residential properties. Aintree sits at a low elevation of around 15 metres, close to the River Alt and the M57 and M58 motorways. Aintree is located near several other communities, including Waddicar, Melling, and Kirkby Park, and is about 5 miles from Liverpool city centre. Aintree has a population of approximately 2708 people, according to recent estimates.
Fuel drain cover in Aintree and across Merseyside
Waddicar, Melling and Kirkby Park are among the places around Aintree that the same teams work, answering petrol in diesel jobs across Aintree's L postcode area. The car does not need to come to us: we drain at a forecourt, in a supermarket car park, in a lay-by or on your own driveway.
Still at the pump around Aintree?
Then you're in the best spot there can be. Phone, and leave it switched off.