How Worried Should You Be? Petrol in a Diesel Car in Westwells
Provided it has not been started, worry less than you probably are. Petrol resting in a diesel tank does nothing to your engine till something draws it through the fuel system — your ignition priming the pump, your starter, or driving on its own. So the truthful answer to the first question anyone around Westwells asks, "have I ruined it?", is usually no. Petrol in Diesel is who to ring, with the motor left off, and so it remains that way. Keep reading for three things: the effect petrol has inside a diesel motor, the clues of how far it has spread, and ways to make sure you don't repeat it.
Petrol in a diesel: what does it do to the engine?
Two jobs fall to diesel on its journey through a motor. Before it combusts, it lubricates — and then it burns. Extremely fine clearances go into the injectors and the high-pressure pump, and only your diesel running through stops those surfaces grinding together.
Badly at the first, not at all at the second: that is petrol. Being less viscous than diesel, petrol strips away the lubrication a fuel system needs, leaving a pump running on that mixture wearing itself. It's equally made to resist igniting under compression — the reverse of what a diesel needs — which is where you hear the knocking.
The shape of the trouble is clear when you put those together. Not contact but circulation is what does the damage. All a tank with petrol in it amounts to is a fuel fault. A pump that has been labouring on that petrol is the beginning of a mechanical one, and whatever a worn pump sheds moves on with your fuel to the fuel injectors downstream.
How bad is petrol in a diesel? Four situations our engineers see in Westwells
Filled up, and not started: nothing beats it. Being on a forecourt is what makes this possible: elsewhere, the vehicle has been driven there to begin with. With the petrol held in the tank alone, it's drained and flushed on the spot, and nothing more is needed.
Started for a moment, or just the ignition on. The system has been primed, so petrol has left that tank and reached your filter and the lines. Still generally easy: drain, flush, and the fuel filter sorted.
Driven a few miles. Now your pump has spent those miles working on thinned fuel. Tank, lines, filter, then fresh fuel put through the entire system: that's the work, and the way the car was driven counts as much as the miles. Driving the children to Neston Primary School is one kind of trip. Driving as far as Bath, under 10 miles away, makes a very different job — as does any mileage on the M4, under 10 miles from Westwells, with the engine labouring hard all the way.
Driven until it protested. Clattering, a ragged idle, smoke, a throttle that has gone soft. The engine is telling you the fuel is no longer behaving like diesel. Pull up wherever you are — the verge on Moor Green, a lay-by, a side street — and leave the car there. What goes first is still the drain and flush, and that deals with it, with long-term damage very uncommon when a car is pulled over early.
Myths Westwells people hear about petrol in a diesel
"Top it up the rest of the way with diesel and it will be fine" — a myth. It won't. A fuller tank of the same mix is all it gives, since topping up removes nothing. That advice assumes a diesel fuel system handles petrol by percentage. It does not.
Myth: a newer diesel copes with a bit of petrol. Rather, the reverse. Finer parts and higher pressure are the way a modern diesel runs its fuel, and that makes the protection count more, not less.
One myth that catches drivers off guard: if it starts and drives, it must be unharmed. A petrol engine fed diesel normally will not run, and so the motorist stops and the damage stops with them. Feed petrol to a diesel and it generally starts, ticks over and drives away as if nothing happened — all the while its pump is wearing. A running engine does not mean fine.
Myth: "Add some two-stroke oil and drive the vehicle home." It's an old workaround for a separate fault. None of what petrol thinned is put back by it — and afterwards, that tank still contains the petrol.
The next start draws petrol back round your pump out of your lines and the fuel filter, where some of it ends up once the engine has run. That's why draining your tank yourself doesn't leave you sorted — a myth. It's also genuinely dangerous to drain petrol into a can at the kerbside.
How does petrol in a diesel occur?
It is rarely carelessness, and no one does it on purpose. One way only, since of the nozzles: the smaller petrol one slips inside a diesel filler with almost no resistance, whereas the diesel one mostly won't fit a petrol car. That's how the forecourt makes it easy.
Habit and your car getting out of step is when it happens. A new motor, a hire car or a courtesy car. Two motors on one drive, one petrol, one diesel. The pumps in a different order on a familiar forecourt. A train to catch, and a hurried fill en route to Melksham. A new-to-you diesel Renault Megane, its first fuelling, and a motorist used to petrol: precisely when it occurs. The hand repeats what it has always done once you add rain, a phone call or a back seat full of kids.
Next time you fill up in Westwells: preventing petrol in a diesel
- 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, so check it on your first fill in any motor you don't know.
- Good intentions count for less than a sticker or a fob in a bright colour on the diesel's key when a home has one of each. So label it.
- It seems daft and it works: on your first fill in a new or hired car, say "diesel" aloud before you lift the nozzle off the pump.
- Mistakes like this are easy to make while your mind is on something else, so your phone goes away.
- Some diesels have a filler designed to refuse a petrol nozzle, and devices you can add are available for cars without one. Such an inhibitor helps up to a point — as a safety net, not a reason to stop reading the pump.
- Less petrol makes a thinner mixture, and so stop as soon as you realise — though remembering that the next step is unchanged. It is still not to fire it up.
Westwells: already put petrol in a diesel?
The order of things is brief, then. Leave it unstarted, with the ignition switched off too. Still on the forecourt, at Texaco or anywhere else? Ask the staff to help you push it away from the pump. What went in, about how much, and if it has run: tell us that when you call 0333 366 0103.
AdBlue, not petrol? Then say so. Corrosion and deposits, not lost lubrication, make it a separate problem — Westwells has a page all for it.
Why one petrol in a diesel job around Westwells costs more than another
The four situations above are four different jobs, so no single quote for this would be honest. The scenario itself does most of the work of moving your cost. Two things follow that: the petrol that got in as a proportion of what that tank holds, then the spot the vehicle is in and whether our van can get to it safely.
Ahead of any quote, not after, come three questions: the fuel that got in, its amount, and whether it's run. That's why. Given those answers, there is a straight figure rather than a range.
About Westwells, briefly
Westwells is a suburban area in Wiltshire, situated inland at an elevation of 106 metres, approximately 6.8 miles from the city of Bath. Westwells is characterized by its predominantly detached housing stock, with nearby places including Greenhill, Neston, and Hudswell. Westwells is located in the South West region of England, about 89.9 miles from London.
Across Wiltshire and in Westwells: fuel drain cover
Petrol in diesel call-outs around Westwells — part of the SN postcode area — go to teams that also cover the places around it, Greenhill, Neston and Hudswell among them. The car doesn't need to come to us: we drain on a forecourt, in a supermarket car park, in a lay-by or on your own driveway.
In Westwells and still at the petrol pump?
Then you're in the best place there can be. Keep it off. Ring.