Should You Worry? Petrol in a Diesel Car in Lusty
Likely less than you are now — provided no one has started it. "Have I ruined it?" is the first thing anyone around Lusty asks, and the truthful answer is normally no, because petrol left in a diesel tank hurts nothing till it's dragged through your fuel system — by ignition priming, by your starter, or by driving. To keep the car like that, call Petrol in Diesel and leave your engine alone. The remainder of this page sets out what petrol actually does to a diesel, how to judge how far it has got, and how to make sure it doesn't happen to you a second time.
What petrol in a diesel does to your engine
On its way through an engine, diesel has two tasks. It ignites, and before it combusts it lubricates. Very fine gaps go into the injectors and your high-pressure pump, and just your diesel flowing through stops those surfaces grinding together.
Of those two tasks, petrol handles the first poorly and the second never. It's thinner than diesel and strips away the protection the system hinges on, so a pump running on a petrol mixture is a pump wearing itself. And petrol is designed to resist igniting under compression, which is the opposite of what a diesel needs from its fuel. That's where the knocking comes from.
The shape of the problem is clear once you put those together. Not contact but movement is what does the harm. All a tank with petrol in it amounts to is a fuel fault. After the pump has been running on that petrol, a mechanical problem has started: anything shed by a pump that is wearing is carried onward to the injectors with the fuel.
Petrol in a diesel in Lusty: how bad is it? Four cases
Filled up, and never started: nothing beats it. Being at a forecourt is what makes this the case: elsewhere, the car has been driven there to begin with. With the petrol kept in the tank alone, it's emptied and cleaned right where it stands, and nothing more is needed.
A brief spell of running, or merely the ignition on. With your system primed, the lines and filter now hold petrol that came from your tank. Still usually simple: drain, flush, and the fuel filter seen to.
A couple of miles driven, and the pump has spent each of them working on weakened fuel. Miles is only half of that; how hard it was driven counts just as much. Either way this work runs to your tank, the fuel lines, the filter and clean fuel through the entire circuit. Driving the children to Bruton Primary School is one sort of trip. Driving as far as Wells, under 15 miles away, makes a very different job — as does any distance on the M5, under 25 miles from Lusty, with the engine running hard the whole time.
Driven on until it complained — knocking, smoke, an uneven idle, a soft throttle. What you are hearing is the engine reporting fuel that no longer runs like diesel. Whether it is the verge on Dropping Lane, a lay-by or a side street, stop where you are then leave it. The drain and flush still go first, and they deal with it: when a vehicle is stopped early, permanent damage is very unusual.
Myths Lusty motorists hear about petrol in a diesel
False: topping up to full with diesel makes it fine. It doesn't. Topping up removes nothing; it gives you a fuller tank of the same mix. Percentage isn't how a diesel fuel system tolerates petrol, whatever that advice supposes.
If anything, the reverse is true. Myth: "A newer diesel can cope with a bit of petrol." At higher pressure, through smaller parts: that is how a current diesel moves its fuel, and so the lubrication counts more, not less.
One myth that catches drivers out: if it starts and drives, it must be unharmed. Any petrol motor fed diesel usually will not run, so the driver stops and the damage stops with them. Feed petrol to a diesel and it normally starts, idles and drives away as if nothing happened — all while its pump wears. A running engine doesn't mean fine.
An old fix for a different issue lies behind this one. Myth: "Add some two-stroke oil and drive the car home." That petrol is still inside that tank afterwards, and whatever it has thinned isn't put back.
The next start draws petrol back round your pump out of your lines and the filter, where some of it sits once the engine has run. That's why a DIY tank drain does not sort it — a myth. Clearing petrol into a can at the roadside is also truly hazardous.
How does petrol in a diesel take place?
On purpose? Never. Through carelessness? Seldom, if ever. A diesel nozzle mostly will not go into a petrol car, but the slimmer petrol nozzle goes into the filler of a diesel almost without resistance — so forecourts make this one error straightforward, and just in that direction.
Routine and your car falling out of step is how it happens. Hire cars, courtesy cars, and cars that are new to you. Two cars on one drive, one petrol, one diesel. A familiar forecourt with the pumps in a different order. Fuelling up in a hurry en route to Bruton, with a train to catch. Years of petrol motors behind you, a diesel Volkswagen Passat in front of you at the forecourt for its first tank — that's when. With rain, a call arriving, or children to deal with, the hand simply does what it always has.
Lusty drivers: how to avoid petrol in a diesel next time
- Read the petrol pump, not the colour. In the UK unleaded handles are generally green and diesel black, but not on each forecourt. The label is what counts.
- Inspect your filler flap. Many vehicles state the fuel type inside the flap or on the cap. Look at it on your first fill in a car you don't know.
- One of each in the home? Mark your key to the diesel — a coloured fob, a sticker — since meaning to remember isn't enough.
- It sounds 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.
- Tuck the phone away. This is an easy mistake to make whilst you are thinking about something else.
- A misfuel inhibitor helps, up to a point. Some diesels have a filler built to reject a petrol nozzle, and add-on devices exist for vehicles without one. They are a safety net, not a reason to stop reading the pump.
- Noticing it mid-fill? Stop at once. A thinner mixture results from less petrol inside the tank, yet the next stage stays the same: do not crank it.
Put petrol in a diesel in Lusty already?
In that case, there is just a short order of things. Don't turn the ignition on, and don't crank it. Ask the attendants to help you push it away from the petrol pump if you're still at the forecourt, whether that's Esso or anywhere else. Next, 0333 366 0103. We'll ask what was put in, about how much, and if it has been run.
If it was AdBlue rather than petrol, say so. That is a different problem — corrosion and deposits rather than lost protection — and it has its own page for Lusty.
Lusty petrol in a diesel jobs: why one costs more than another
There is no honest single price for this, since the four scenarios above are four separate tasks. What shifts the cost is chiefly which of them you are in. Beyond that it's the ratio — how much petrol was put in against how much the tank takes — and then where the car is and whether a van can reach it safely.
Three queries come first, before quoting, instead of after — what went in, how much, has it run — and this is the reason. Those answers turn a range into a straight figure.
About Lusty, briefly
Lusty is a small riverside locality in Somerset, situated near the cities of Wells and Bruton. Lusty sits at an elevation of 84 metres, with the surrounding countryside dominated by the River Brue. Lusty has a mix of housing types, but terraced homes are particularly prevalent in the area. Lusty is located approximately 10.9 miles from Wells and 104.1 miles from London.
Fuel drain cover around Lusty and across Somerset
Lusty waits in the BA postcode area, and our vans that answer petrol in diesel calls there work the spots around it as well — Bruton, Tolbury and Discove among them. You need not bring the vehicle to us. Forecourts, supermarket car parks, lay-bys and your own drive are all places where we work.
Lusty: still at the petrol pump?
The best position there is, then — that is where you are. Phone, and leave it turned off.