Houghton: Petrol in a Diesel Car? How Worried to Be
Unstarted? Then less worried than you likely are. "Have I wrecked it?" is the first question everyone around Houghton asks, and the truthful answer is generally no, because petrol resting in a diesel tank hurts nothing till it is dragged through your fuel system — by ignition priming, by your starter, or by being driven. To keep it that way, phone Petrol in Diesel and leave the motor switched off. Read on for three things: the effect petrol has inside a diesel motor, the clues of how far it has got, and ways to make sure you don't do it again.
What petrol in a diesel does to the motor
Passing through an engine, diesel does two things at the same time. It combusts, and before it burns it protects. Your high-pressure pump and the fuel injectors are designed to extremely fine tolerances, and your diesel passing through them is what stops those surfaces from wearing against one another.
Of those two tasks, petrol manages the first poorly and the second never. The rattling comes from petrol being made not to ignite when compressed, which is precisely the opposite of what a diesel needs. On top of that it is thinner than diesel, it strips away the lubrication the system hinges on, and any pump running on that mix is wearing itself.
Combined, those make the shape of the trouble clear. It is movement that does the damage, not contact. Petrol in the tank is a fuel fault. After your pump has been labouring on that petrol, a mechanical problem has started: whatever is shed by a pump that's grinding is carried downstream to the fuel injectors with your fuel.
Houghton, petrol in a diesel: four cases, from mild to serious
Filled up, and not started: no case is better. The petrol is in the tank and only your tank, and the task is a drain and a flush where the car sits. This is the one situation that can only really occur at a forecourt, because anywhere else the vehicle has been driven to get there.
The ignition turned on, or a short start. With your system primed, the lines and filter now contain petrol that has come from that tank. Usually little more than draining, purging and seeing to the fuel filter, and so still simple.
Your pump has worked a few miles on thinned fuel — that is what driving the vehicle does. The work is that tank, your lines, the fuel filter and clean fuel through the whole system, and how hard the vehicle was driven counts as much as how far. Short trips, like the school run to Houghton CofE School, are one matter. A run as far as Carlisle, under 3 miles away, is a very different job. So is any miles on the M6, under a mile from Houghton, where the motor has been running hard the whole time.
It complained, and only then stopped: smoke, rattling, a throttle gone soft, an idle gone ragged. What you are hearing is the motor signalling fuel that no longer acts like diesel. Leave it where it has stopped: a lay-by, a side street, the verge on Orchard Lane. A vehicle pulled over early very seldom has long-term damage, as the drain and the flush-through, which still go first, sort it out.
What Houghton drivers get told about petrol in a diesel — and the myths in it
Myth: "Fill it the rest of the way with diesel and it'll be fine." It will not. Nothing is removed by topping up — you're left with a bigger tank, still the same mix. The idea behind that guidance — that diesel fuel systems accept petrol by percentage — is wrong.
Myth: "A newer diesel can cope with a bit of petrol." If anything, the reverse. Lubrication matters more on newer diesels, not less, since their fuel runs through finer components at higher pressure.
Myth: "If it starts and drives, there's no damage done." This is the one that catches motorists. Feed diesel to a petrol motor and it normally won't run, so the driver stops — and the damage stops with them. A diesel fed petrol normally starts, ticks over and drives away as though nothing has happened, while your pump wears. Being able to run isn't the same as being fine.
"A drop of two-stroke oil and drive it home" — a myth, taken from a fix from years ago, for a different issue. None of what petrol thinned gets put back by it — and later, your tank still contains that petrol.
"Drain it yourself and you are sorted" — a myth, since after it's been running some petrol sits in your filter and lines, waiting to go straight back through your pump on your next start. It is also really hazardous to drain petrol into a can at the kerbside.
Petrol in a diesel: how does it occur?
No one does it on purpose, and it's seldom carelessness. A diesel nozzle mostly won't fit a petrol vehicle, yet the smaller petrol nozzle goes into the filler of a diesel nearly without resistance — so forecourts make this one mistake simple, and just in one direction.
Routine and the car falling out of step is how it occurs. Courtesy car, hire car, or a motor that is brand new. Households running one of each, petrol and diesel. A familiar forecourt with the pumps in a different order. A hurried fill on the way to Carlisle with a train to catch. A new-to-you diesel Volkswagen Passat, its first fuelling, and a motorist accustomed to petrol: exactly when it happens. With rain, a call coming in, or a car full of children to deal with, the hand just does what it always has.
Next time you fill up around Houghton: preventing petrol in a diesel
- Green for unleaded and black for diesel is normal in the UK — yet not on every forecourt. Trust the label on the petrol pump, not the colour.
- The first fill in an unfamiliar vehicle is the time to check the filler flap — on it, or on the cap, plenty of motors state which fuel to use.
- One of each in the home? Mark the key to the diesel — a coloured fob, a sticker — since meaning to remember is not enough.
- Say it before you lift it. On the first fill in a new or hired car, say "diesel" out loud before you take the nozzle off the petrol pump. It sounds silly and it does the trick.
- Put your phone away. This is an easy mistake to make whilst you're thinking about something else.
- Add-on devices exist for motors without one, and some diesels come with a filler that will not accept a petrol nozzle. Helpful — but a safety net only, never a reason to stop checking the label.
- The moment you notice, stop: less petrol inside that tank makes a weaker mixture. What to do next does not change, though — still don't fire it up.
Put petrol in a diesel around Houghton already?
Short and simple, then, is the order of things. Leave it unstarted, with your ignition switched off too. Yet on the forecourt, at BP or anywhere else? Ask the staff to help you push it clear of the petrol pump. What went in, about how much, and whether it's run: tell us that when you phone 0333 366 0103.
Corrosion and deposits form the issue with AdBlue, whereas petrol brings lost lubrication. So if it was AdBlue, say so — and read its own Houghton page.
One petrol in a diesel job in Houghton costs more than another. Why?
The four situations above are four separate jobs, so no single price for this would be honest. Chiefly, your cost shifts with which situation you're in. Where the car is matters too, and whether a van can safely reach it, after the proportion of petrol to what your tank takes.
Three queries come first, before any quote, instead of after — what went in, how much, has it run — and this is the reason. A range turns into a straight figure when those answers are in.
About Houghton, briefly
Houghton is a village situated on the River Eden in Cumbria, with a low elevation of around 29 metres. Houghton lies close to the city of Carlisle, approximately 2.2 miles away, and is near other small settlements such as Brunstock and Tarraby. Houghton has a population of around 804 people, predominantly living in semi-detached housing. Houghton is located in the North West region of England, about 262.9 miles from London.
Fuel drain cover across Cumbria, Houghton included
Petrol in diesel jobs around Houghton — part of the CA postcode area — go to vans that likewise cover the locations around it, Brunstock, Tarraby and Whiteclosegate included. Our engineers drain where your vehicle is — your own driveway, a lay-by, a supermarket car park, a forecourt — so it does not have to come to us.
In Houghton and still at the pump?
No position is better: that is where you now are. Switched off it remains; then call.