How Worried Should You Be? Petrol in a Diesel Car in Bowerhill
Provided it has not been started, worry less than you probably are. Until your ignition primes the pump, your starter cranks, or the vehicle is driven, petrol in a diesel tank just sits there and does nothing. Which means the honest reply to that first Bowerhill question — "have I ruined it?" — usually no. Petrol in Diesel is who to call, with your engine left off, so it stays that way. Further down, this page sets out what petrol actually does inside a diesel, how far it may have got, and how to stop it happening to you again.
Inside the engine: what petrol in a diesel really does
Passing through a motor, diesel does two things at the same time. It ignites, and before it ignites it lubricates. Extremely fine clearances go into your injectors and the high-pressure pump, and just the diesel flowing through keeps those surfaces from grinding together.
The second job petrol does not do at all, and the first it does poorly. Being less viscous than diesel, petrol strips away the lubrication a fuel system needs, so a pump running on the mixture to wear itself. It's also made to resist igniting under compression — the opposite of what a diesel needs — which is why you hear the clattering.
The shape of the issue is plain when you put those together. Not contact but circulation is what causes the harm. Where the petrol is only in the tank, it is a fault of fuel, nothing more. After the pump has been running on that petrol, a mechanical problem has begun: anything shed by a pump that's grinding travels downstream to the fuel injectors with the fuel.
Bowerhill, petrol in a diesel: four cases, from mild to major
Filled but never started — as good as it gets. Just that tank has petrol in it, and so the job is emptying the tank and flushing the fuel system where your car stands. This situation can only truly happen at a forecourt: anywhere else, the vehicle got there by being driven.
The ignition switched on, or a short start. With the fuel system primed, your lines and filter already contain petrol that has come from your tank. Still usually straightforward: drain, flush, and your filter seen to.
Driven a few miles. Now your pump has spent these miles running on diluted fuel. How hard the vehicle was driven matters as much as how far, and the work covers that tank, the fuel lines, your filter and clean fuel through the entire circuit. Short trips, like the school run to Bowerhill Primary School, are one thing. Any distance on the M4, under 15 miles from Bowerhill, means the engine working hard throughout, and a run to Bath, under 15 miles away, makes a very different task too.
Driven until it complained. Rattling, a lumpy idle, smoke, a throttle that has gone soft. The engine is telling you the fuel is no longer acting like diesel. Stop wherever you are — the verge on Gibson Close, a lay-by, a side street — and leave it there. A car pulled over early very seldom has lasting damage, because the drain and the flush, which still come first, sort it out.
Bowerhill people and that petrol in a diesel stories they hear
Myth: "Fill it the rest of the way with diesel and it will be fine." It will not. Nothing comes out when you top up — that tank just carries more of the same blend. Percentage is not how a diesel fuel system tolerates petrol, however much that guidance assumes.
If anything, the reverse holds. Myth: "A current diesel can cope with a bit of petrol." At higher pressure, through smaller parts: that is how a modern diesel moves its fuel, so the lubrication matters more, not less.
Myth: "If it starts and drives, there is no damage done." This is the one that fools motorists. Any petrol engine fed diesel normally will not run, so the driver stops and the harm stops with them. Nothing looks to have happened when a diesel fed petrol fires up, ticks over and drives away, as it usually does; meanwhile the pump wears. Fine and running are not the same at all.
An outdated fix for a different problem is behind this one. Myth: "Add some two-stroke oil and drive the car home." It does not put back what petrol has diluted, and the petrol is still inside the tank later.
Myth: "Drain that tank yourself and you're sorted." After your engine has run, some of the petrol is no longer inside your tank: it's in your filter and your lines, and it goes straight back through the pump at the next start. Also, a can of petrol filled at the kerbside is truly risky.
How it happens: petrol in a diesel
No one does it on purpose, and it is seldom carelessness. One way only, since of the nozzles: the narrower petrol one slides inside a diesel filler with almost no resistance, while the diesel one generally will not fit a petrol car. That is how the forecourt makes it easy.
Habit and the vehicle getting out of step is how it occurs. Any motor that's new to you — a hire car, on loan as a courtesy car, or brand new. A household with one petrol and one diesel on the driveway. A well-known forecourt with the pumps in a different order. A rushed fill en route to Melksham with a train to catch. Exactly the moment it happens: after years of driving petrol, someone fills a diesel Renault Clio for the first time. Add rain, a phone call or a back seat full of children, and your hand does what it has always done.
Bowerhill people: how to prevent petrol in a diesel next time
- The label is what counts, and so check the pump instead of the colour: in the UK unleaded handles are normally green and diesel black, yet not on each forecourt.
- Plenty of cars state the fuel type inside your filler flap or on the cap, and so check there on your first fill in a motor you don't know.
- Mark your key. In a house with one of each, a coloured fob or a sticker on your diesel's key does more than any amount of intending to remember.
- It seems silly and it does the trick: on your first fill in a new or hired car, say "diesel" out loud before you take the nozzle off the pump.
- Thinking about something else is when this becomes an easy mistake to make, so tuck the phone away and keep your mind on the pump.
- Some diesels have a filler built to block a petrol nozzle, and devices you can add exist for motors without one. Such an inhibitor helps up to a point — as a backstop, not a reason to stop checking the petrol pump.
- Stop the moment you notice. Less petrol in that tank means a weaker mix. It does not change what to do next, which is still not to fire it up.
Bowerhill: already put petrol in a diesel?
The order of things is short, then. Do not start the car, and don't turn your ignition on. If you're still on the forecourt — Texaco or anywhere else — ask the attendants to help you push it away from the pump. Next, 0333 366 0103. We'll ask what was put in, about how much, and if it has been run.
Say so if it was AdBlue instead of petrol: it's a separate fault, with its own page for Bowerhill, because AdBlue brings corrosion and deposits rather than lost protection.
Why one petrol in a diesel job in Bowerhill costs more than another
A fair single price doesn't exist here: four situations, four separate jobs. Mostly, the cost shifts with which one you are in. Where the vehicle is counts too, and whether our van can safely get to it, after the ratio of petrol to what your tank holds.
Three queries come first, before any quote, instead of after — what went in, how much, has it run — and that is the reason. Given those replies, you get a straight figure rather than a range.
About Bowerhill, for a moment
Bowerhill is a village in Wiltshire, situated inland at an elevation of around 50 metres, approximately 10 miles from the city of Bath. Bowerhill is characterized by its predominantly detached housing stock and is located near other small settlements such as The Spa, Berryfield, and Outmarsh. Bowerhill has a population of around 2560 residents and is about 86 miles west of London.
Bowerhill and Wiltshire: where our fuel drain cover reaches
The teams answering petrol in diesel calls in Bowerhill, in the SN postcode area, equally work the locations around it, The Spa, Berryfield and Outmarsh included. Our engineers drain wherever the car is — your own drive, a lay-by, a supermarket car park, a forecourt — so it does not have to come to us.
Still at the petrol pump in Bowerhill?
No position is better: that's where you now are. Phone, and keep it turned off.