Petrol in a Diesel Car in Braunston: How Worried Should You Be?
Probably less than you are now — provided no one has started the car. "Have I wrecked it?" is the first question anyone in Braunston asks, and the honest answer is usually no, since petrol left in a diesel tank hurts nothing until it's dragged through your fuel system — by ignition priming, by your starter, or by driving. Petrol in Diesel is who to call, with the engine kept off, so it stays that way. The remainder of this page covers what petrol really does to a diesel, how to judge how far it has got, and how to make sure it doesn't happen to you again.
What petrol in a diesel does to the motor
Diesel does two tasks on its way through an engine. Lubricating comes before burning; it does both. The high-pressure fuel pump and the injectors are made to very fine gaps, and the diesel passing through them is what stops those surfaces from grinding against one another.
Petrol does the first job badly and the second not at all. A pump working on a petrol blend is wearing itself out, because petrol is runnier than diesel and takes away the protection your fuel system relies on. Petrol is also designed to resist igniting under compression — the opposite of what a diesel wants from its fuel — and that is where any knocking comes.
Combined, those make the shape of the trouble clear. Contact does not do the damage — circulation does. Petrol in a tank is a fuel problem. Whatever a worn pump sheds travels on, carried by your fuel, into your injectors downstream, which is why a pump that has been working on the petrol is where a mechanical issue begins.
Four scenarios our engineers see around Braunston: how serious is petrol in a diesel?
Filled but not once started — the best it gets. Only that tank has petrol in it, so the job is draining the tank and rinsing the fuel system where your car sits. This scenario can only really occur on a forecourt: anywhere else, the vehicle got there by being driven.
Started for a second, or just the ignition on. With the system primed, the fuel lines and filter already contain petrol that came from your tank. Usually nothing more than clearing, cleaning and seeing to your filter, so still simple.
Those few miles driven were the pump running on fuel diluted by petrol the whole way. Distance is only half of it; how hard it was driven counts equally. Either way the work includes that tank, your lines, your filter and fresh fuel through the whole circuit. The school run to Braunston Church of England Primary School is one matter. Very different again: a run to Coventry, under 25 miles away, or any distance on the M45, under 5 miles from Braunston, where your engine never stopped working hard.
Driven on till it complained — knocking, smoke, a lumpy idle, a soft throttle. What you are hearing is the engine signalling fuel that no longer acts like diesel. Stop where you are — on the verge on Cross Lane, at the kerb, down a side road — and don't move it. A car stopped quickly very rarely has permanent damage, since the drain and the flush-through, which still come first, take care of it.
What Braunston motorists get told about petrol in a diesel — and the myths in it
"Top it up the rest of the way with diesel and it'll be fine" — a myth. It will not. A bigger tank of the same mix is all it gives, since topping up removes nothing. That advice supposes a diesel fuel system handles petrol by percentage. It does not.
Myth: "A newer diesel can cope with a bit of petrol." If anything, the reverse. Finer components and higher pressure are how a current diesel runs its fuel, and that makes the lubrication count more, not less.
"It starts, it drives, and so there is no harm" — the myth that catches more people than any other. Feed diesel to a petrol motor and it generally won't run, and so the driver stops — and the harm stops with them. Whilst your pump wears, a diesel fed petrol usually starts, ticks over and drives away as if nothing has happened. Fine and running aren't the same thing.
Myth: a two-stroke additive lets you to drive home. It is an old workaround, supposed for another issue. What petrol has thinned stays thinned, and that petrol stays in the tank regardless.
Once the engine has been run, part of that petrol is in the fuel filter and the lines, not your tank — and the next start sends it right back through the pump. So the myth "drain that tank yourself and you are sorted" does not hold. Draining petrol into a can by the roadside is also genuinely hazardous.
Why petrol in a diesel happens at all
A careless moment is seldom the cause, and nobody means to do it. One way only, because of the nozzles: the narrower petrol one slides inside a diesel filler with almost no resistance, whereas the diesel one mostly won't fit a petrol motor. That is how the forecourt makes it straightforward.
The moment routine stops matching the car is the moment it happens. A new vehicle, a hire car or a courtesy car. A household with one petrol and one diesel on the drive. A forecourt you know, but with its pumps laid out differently. A train to catch, and a hurried fill en route to Long Buckby. A new-to-you diesel Renault Megane, its first fuelling, and a motorist accustomed to petrol: exactly when it occurs. Throw in a back seat full of children, a phone call or rain, and habit wins.
Next time you fill up around Braunston: preventing petrol in a diesel
- Green for unleaded and black for diesel is usual in the UK — but not on every forecourt. Go by the label on the petrol pump, not the colour.
- Inspect your filler flap. Plenty of vehicles state the fuel inside the flap or on the cap. Look at it on the first fill in any motor you do not know.
- One of each in the household? Mark your key to the diesel — a bright fob, a sticker — because 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 lift the nozzle off the petrol pump. It sounds silly and it works.
- Put the phone away. This is an easy mistake to make whilst you are thinking about something else.
- Add-on devices are available for cars without one, and some diesels are built with a filler that won't accept a petrol nozzle. Helpful — but a backstop at best, never a reason to stop checking the label.
- As soon as you realise, stop: less petrol in the tank makes a thinner mix. What to do next does not change, though — still do not start it.
Put petrol in a diesel around Braunston already?
Then the order of things is brief. Do not switch your ignition on, and don't start it. Still on the forecourt, at Gulf or anywhere else? Ask the staff to help you push the vehicle clear of the pump. What was put in, roughly how much, and whether it has run: tell us those when you call 0333 366 0103.
Say so if it was AdBlue rather than petrol: it is a different issue, with its own page for Braunston, since AdBlue brings corrosion and deposits instead of lost protection.
Why one petrol in a diesel job in Braunston costs more than another
There's no fair single price for this, since the four situations above are four separate tasks. Chiefly, the cost shifts with which one you're in. The share matters next, meaning how much of that tank is petrol, followed by the location of the car and whether reaching it is safe for our van.
Three queries come first, before quoting, instead of after — what went in, how much, has it run — and this is the reason. Given the answers, there is a straight figure instead of a range.
About Braunston
Braunston is a village in Northamptonshire, situated on the River Oxford Canal and near the River Leam, with a mix of old and new housing including many detached homes. Braunston sits at an elevation of around 127 metres, in a rural area of the East Midlands. Braunston is close to several smaller settlements, including Little Braunston, Wolfhamcote, and Wolfhampcote, and is within commuting distance of major cities like Coventry. Braunston has a population of approximately 1506 people, living in a range of dwellings, predominantly detached houses.
Braunston and Northamptonshire: where our fuel drain cover reaches
The teams answering petrol in diesel calls around Braunston, in the NN postcode area, also work the locations around it, Little Braunston, Wolfhamcote and Wolfhampcote among them. We drain where your vehicle is — your own drive, a lay-by, a supermarket car park, a forecourt — so it does not have to come to us.
In Braunston and still at the pump?
The best position there is, then — that is where you are. Switched off it remains; then phone.