How Worried Should You Be? Petrol in a Diesel Car in Gilmerton
Likely less than you are now — as long as nobody has started the car. "Have I ruined it?" is the first question anyone around Gilmerton asks, and the truthful answer is usually no, because petrol left in a diesel tank harms nothing till it is drawn through the system — by ignition priming, by the starter, or by driving. Keep it like that: leave the motor off and call Petrol in Diesel. What petrol actually does to a diesel, how to judge how far it has travelled, and how to keep it from happening again: that's the rest of this page.
What petrol in a diesel does to the motor
Two tasks fall to diesel on its route through a motor. It lubricates to begin with, and after that does it burn. The high-pressure pump and the fuel injectors are designed to very fine clearances, and the diesel passing through them is what stops those surfaces from grinding against each other.
Poorly at the first, not at all at the second: that's petrol. Being less viscous than diesel, petrol strips out the lubrication a fuel system needs, so a pump on the blend wearing itself. It is equally made to resist igniting under compression — the reverse of what a diesel needs — which is where you get the clattering.
The shape of the issue is plain once you put those together. Not contact but circulation is what does the damage. A tank with petrol in it is a fuel problem. A pump that has been labouring on that petrol is the start of a mechanical one, and whatever a worn pump sheds moves on with the fuel to your injectors further on.
Gilmerton, petrol in a diesel: four situations, from mild to significant
Filled but never started — as good as it gets. On a forecourt, and really only there, the petrol is still limited to that tank — because everywhere else the car was driven to get to it. The task is emptying and purging on the spot.
Started for a second, or only the ignition on. With the fuel system primed, the lines and filter now hold petrol that has come from that tank. Normally little more than clearing, rinsing and sorting the fuel filter, so still simple.
A couple of miles driven, and your pump has spent each of them working on diluted fuel. The work is the tank, your lines, the fuel filter and clean fuel through the entire system, and how hard your car was driven counts as much as how far. A school run to the local primary school is one thing. Getting as far as Edinburgh, under 5 miles away, makes a very different job — as does any miles on the M8, under 10 miles from Gilmerton, with the engine working hard all the way.
Driven on until it protested — clattering, smoke, an uneven idle, a dead throttle. That is the engine telling you its fuel no longer is behaving like diesel. Pull up wherever you are — the verge on Newtoft Street, a lay-by, a side street — and leave the car there. What goes first is still the drain and flush-through, and that sorts it out, with lasting damage very rare when a car is pulled over early.
Myths Gilmerton motorists hear about petrol in a diesel
Myth: topping up to full with diesel makes it fine. It doesn't. Topping up removes nothing; it gives you a bigger tank of the same mixture. Percentage isn't how a diesel fuel system tolerates petrol, however much that advice presumes.
If anything, the reverse holds. Myth: "A newer diesel can cope with a bit of petrol." At higher pressure, through smaller parts: that's how a newer diesel handles its fuel, and so the protection counts for more, not less.
This is the one that fools people. Myth: "If it starts and drives, there is no harm done." The motorist of a petrol motor fed diesel usually stops, because it will not run, and the damage stops with them. A diesel fed petrol usually starts, idles and drives away as though nothing has happened, while your pump wears. Being able to run is not proof of being fine.
Not so: a two-stroke additive makes it safe to drive home. It is an old workaround, meant for another problem. None of what petrol diluted is put back by it — and later, that tank still contains the petrol.
The next start sends petrol back round the pump from the fuel lines and your filter, where some of it ends up after the engine has run. That is why draining your tank yourself does not leave you sorted — a myth. It's also really dangerous to drain petrol into a can at the kerbside.
Why petrol in a diesel takes place at all
On purpose? Never. Through carelessness? Seldom, if ever. The petrol nozzle is the slimmer of the two and slides into a diesel filler with almost no resistance; a diesel nozzle mostly will not go into a petrol car at all. The forecourt makes it easy, and the mistake runs one way.
When habit and the car stop matching, it takes place. A new motor, a hire car or a courtesy car. Two cars on one drive, one petrol, one diesel. The pumps in a different order on a well-known forecourt. Racing for a train at Eskbank and fuelling up en route. Precisely the moment it happens: after years of driving petrol, someone fills a diesel Renault Megane for the first time. Add a back seat full of children, a phone call or rain, and the hand takes over.
Gilmerton motorists: how to prevent petrol in a diesel next time
- Green for unleaded and black for diesel is normal in the UK — but not on each forecourt. Go by the label on the petrol pump, not the colour.
- Check your filler flap. Many vehicles state the fuel inside the flap or on the cap. Look at it on the first fill in a car you do not know.
- Good intentions do less than a sticker or a fob in a bright colour on your diesel's key if a home has one of each. So label it.
- "Diesel", aloud, before you pick up the nozzle — every time a new or hired car gets its first tank. It seems daft. It does the trick.
- Whilst you're thinking about something else, this is an easy mistake to make — so tuck the phone away.
- Some diesels have a filler built to refuse a petrol nozzle, and devices you can add exist for motors without one. Such an inhibitor helps up to a point — as a safety net, not a reason to stop checking the petrol pump.
- Stop as soon as you notice. Less petrol in the tank makes a thinner mix. It doesn't change what to do next, which is still not to fire it up.
Put petrol in a diesel around Gilmerton already?
The order of things is short, then. Leave it unstarted, with the ignition off too. Ask the attendants to help you roll it away from the petrol pump if you are still on the forecourt, whether that's Morrisons or anywhere else. Call 0333 366 0103 next, with three facts — the fuel, the rough quantity, and whether it's run.
Say so if it was AdBlue rather than petrol: it is a separate issue, with its own page for Gilmerton, since AdBlue brings corrosion and deposits instead of lost lubrication.
What makes one Gilmerton petrol in a diesel task cost more than the next
Four separate tasks sit behind the four scenarios above — which is why there is no honest single price. What moves your cost is mostly which of them you are in. Where your car is matters too, and whether a van can safely reach it, after the share of petrol to what the tank holds.
What went in, how much, and whether it's run — three questions our engineers ask before quoting, not after, for precisely that reason. Those replies are what change a range into one firm number.
About Gilmerton and its setting
Gilmerton is a suburban area in the City of Edinburgh, situated near the River Esk and approximately 4 miles southeast of Edinburgh's city centre. Gilmerton sits at an elevation of around 128 metres, with the surrounding landscape dominated by the Pentland Hills. Gilmerton is characterized by its predominantly flat-type housing and is located near other suburban areas such as Gracemount and Moredun.
Gilmerton and City of Edinburgh: where our fuel drain cover reaches
Gracemount, Moredun and Southhouse are among the locations near Gilmerton that the same vans work, answering petrol in diesel jobs across Gilmerton's EH postcode area. A forecourt, a supermarket car park, a lay-by or your own driveway are all places our engineers work, and the car doesn't need to come to us.
Still at the pump in Gilmerton?
Then you're in the best place there can be. Switched off it remains; then phone.