Petrol in a Diesel Car in Waterloo: How Worried Should You Be?
Far less than you probably are, provided it hasn't been started. "Have I wrecked it?" is the first thing everyone around Waterloo asks, and the honest answer is usually no, since petrol left in a diesel tank harms nothing till it's dragged through the system — by ignition priming, by the starter, or by driving. Petrol in Diesel is who to phone, with the motor left off, and so it stays that way. Below, this page sets out what petrol actually does inside a diesel, how far it might have gone, and how to stop it happening to you again.
Inside the motor: what petrol in a diesel really does
Two tasks fall to diesel on its route round a motor. It ignites, and before it ignites it protects. What keeps the surfaces inside your high-pressure pump and the injectors from wearing down against one another is the diesel flowing through them — they are built to extremely fine clearances.
Poorly at the first, not at all at the second: that's petrol. The knocking comes from petrol being made not to ignite when compressed, which is exactly the reverse of what a diesel needs. On top of that it is runnier than diesel, it strips away the lubrication the fuel system hinges on, and any pump running on such a mix is wearing itself.
Put those together and the shape of the problem is clear. The harm is done by circulation, not by contact. All a tank with petrol in it amounts to 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 travels on with your fuel to the injectors further on.
Four situations our engineers see in Waterloo: how bad is petrol in a diesel?
The best case there can be: filled up, not once started. The petrol is in that tank and just your tank, and the job is a drain and a flush where the vehicle stands. This is the one scenario that can only really occur at a forecourt, as anywhere else the vehicle has been driven to get there.
Ignition on, or started for a second. With your system primed, the lines and filter now hold petrol that has come from the tank. Usually nothing more than clearing, cleaning and seeing to the fuel filter, and so still straightforward.
Those few miles driven meant your pump running on fuel thinned by petrol throughout. Tank, lines, filter, then clean fuel put through the whole system: that is this work, and the way your car was driven counts as much as the miles. The school run to Dalton School is one thing. A run as far as Bradford, under 15 miles away, is a very different task. So is any mileage on the M62, under 5 miles from Waterloo, where your engine has been working hard throughout.
Rattling, an uneven idle, smoke, a throttle gone soft: driven until it complained. What you are hearing is your engine signalling fuel that no longer behaves like diesel. Whether it's the verge on Waterloo Road, a lay-by or a side road, stop where you are then leave it. A vehicle stopped soon very rarely has long-term damage, since the drain and the flush, which still come first, deal with it.
Petrol in a diesel myths Waterloo motorists hear
It will not be fine. The myth: "Fill it the rest of the way with diesel and it will be." Topping up removes nothing; it gives you a fuller tank of the same mix. Percentage isn't how a diesel fuel system tolerates petrol, however much that advice assumes.
Myth: "A newer diesel can cope with a bit of petrol." If anything, the opposite. At higher pressure, through finer parts: that's how a modern diesel handles its fuel, so the protection matters more, not less.
One myth that catches drivers out: if it starts and drives, it must be unharmed. The motorist of a petrol engine fed diesel normally stops, because it will not run, 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 will; meanwhile the pump grinds. Running isn't the same as fine.
"A drop of two-stroke oil and drive it home" — a myth, borrowed from a fix from years ago, for a different problem. It doesn't put back what petrol has thinned, and the petrol is still in the tank after that.
Once your engine has been run, part of that petrol sits in the fuel filter and the lines, not that tank — and the next start pulls it straight back through your pump. So the myth "drain that tank yourself and you are sorted" doesn't hold. And, a can of petrol filled by the kerbside is truly risky.
Why petrol in a diesel happens at all
No one does it on purpose, and it's seldom carelessness. A diesel nozzle mostly will not fit a petrol vehicle, yet the narrower petrol nozzle goes into the filler of a diesel nearly without resistance — so forecourts make this one error easy, and only in that direction.
The moment routine stops matching the car is the moment it takes place. Courtesy car, hire car, or a car that is brand new. One petrol and one diesel on the driveway of the same household. Your normal forecourt, its pumps suddenly in a different order. Filling up in a rush en route to Deighton, with a train to catch. A new-to-you diesel Volkswagen Golf, its first fuelling, and a driver used to petrol: precisely when it takes place. Your hand does what it has always done when you add rain, a phone call or a back seat full of children.
Waterloo motorists: how to prevent petrol in a diesel next time
- The label is what matters, and so check the pump rather than the colour: in the UK unleaded handles are usually green and diesel black, but not on every forecourt.
- Plenty of vehicles state the fuel type inside the filler flap or on the cap, and so check there on your first fill in a motor you do not know.
- 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 intending to remember.
- It seems daft and it works: on your first fill in a new or hired car, say "diesel" out loud before you lift the nozzle off the pump.
- Thinking about something else is when this becomes an easy mistake to make, and so put the phone away then keep your mind on the petrol pump.
- Some diesels come with a filler built to reject a petrol nozzle, and devices you can add are available for cars without one. Such an inhibitor helps up to a point — as a backstop, not a reason to stop reading the petrol pump.
- The moment you realise, stop: less petrol in that tank makes a weaker mix. What to do next doesn't change, though — still do not start it.
Petrol already in a diesel in Waterloo? Start here
Then the order of things is brief. Do not start the car, and do not switch the ignition on. Ask the staff to help you roll it clear of the pump if you're still at the forecourt, whether that's Morrisons or anywhere else. Next, 0333 366 0103. We will ask what went in, about how much, and if it's been run.
If it was AdBlue and not petrol, say so. That is a separate issue — corrosion and deposits and not lost protection — and it has its own page for Waterloo.
What makes one Waterloo petrol in a diesel job cost more than the next
Four separate tasks sit behind the four scenarios above — which is why there is no honest single price. The scenario itself does most of the work of moving the cost. Two things come after that: the petrol that went in as a proportion of what your tank holds, then the place the car is in and whether our van can reach it safely.
What got in, how much, and whether it has run — three questions our engineers ask before pricing, not after, for precisely that reason. A range turns into a straight figure when the replies are in.
About Waterloo and where it is
Waterloo is a suburban area in West Yorkshire, situated on the riverside at an elevation of 72 metres. Waterloo lies approximately 10 miles from Bradford and is surrounded by nearby places such as Tandem, Cowmes, and Greenside. Waterloo has a population of around 5366 people and predominantly features semi-detached housing. Waterloo is located 162.4 miles north of London, in the Yorkshire and the Humber region.
Waterloo and West Yorkshire: where our fuel drain cover reaches
Tandem, Cowmes and Greenside are among the locations around Waterloo that the same teams work, answering petrol in diesel jobs across Waterloo's HD postcode area. The car does not need to come to us: our engineers drain on a forecourt, in a supermarket car park, in a lay-by or on your own driveway.
Still at the pump around Waterloo?
In that case, you could not be in a better place. Turned off it remains; then call.