Southville: Petrol in a Diesel Car? How Worried to Be
Far less than you probably are, provided it has not been started. Petrol resting in a diesel tank does nothing to the engine until something draws it through the system — your ignition priming your pump, the starter, or the drive on its own. So the fair answer to the first question everyone in Southville asks, "have I ruined it?", is normally no. Petrol in Diesel is who to phone, with the motor kept off, and so it stays that way. Below, 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 your engine: what petrol in a diesel does
On its way through an engine, diesel has two tasks. Lubricating comes before burning; it does both. The high-pressure fuel pump and your injectors are designed to very fine tolerances, and your diesel passing through them is what keeps those surfaces from wearing down against each other.
The second task petrol doesn't do at all, and the first it does poorly. Being less viscous than diesel, petrol strips out the lubrication a fuel system needs, so a pump running on the blend to wear itself. It's also made to resist igniting under compression — the opposite of what a diesel needs — which is where you hear the clattering.
Together, those leave the shape of the issue plain. The harm is done by movement, not by contact. All a tank with petrol in it amounts to is a fuel issue. Once your pump has been labouring on that petrol, a mechanical fault has started: anything shed by a pump that's grinding is carried downstream to your injectors with your fuel.
Four situations our technicians see around Southville: how serious is petrol in a diesel?
Filled but not once started — the best it gets. Being at a forecourt is what makes this possible: elsewhere, your car has been driven there to begin with. With the petrol kept in the tank alone, it's cleared and cleaned on the spot, and nothing more is needed.
A moment's running, or merely your ignition on. Petrol has come out of the tank and got to your filter and the fuel lines, because the system has been bled. Drain, flush, deal with the fuel filter: still normally simple.
Those few miles driven were the pump working on fuel weakened by petrol the whole way. How hard your car was driven matters as much as how far, and this work takes in your tank, your lines, your filter and fresh fuel through the whole circuit. Short trips, such as the school run to Kingsbridge Primary School, are one thing. Very different once more: a trip to Plymouth, under 25 miles away, or any distance on the M5, under 50 miles from Southville, where the motor never stopped working hard.
It protested, and only then stopped: smoke, rattling, a throttle gone soft, an idle gone ragged. What you are hearing is the motor reporting fuel that no longer behaves like diesel. Pull up wherever you are — the verge on Higher Warren Road, a lay-by, a side street — then leave the car there. Lasting damage is very uncommon if a vehicle is stopped soon, and the fuel drain and flush-through that still come first deal with it.
Southville drivers and the petrol in a diesel stories they hear
False: topping up to full with diesel makes it fine. It doesn't. Nothing is removed by topping up — you're left with a bigger tank, still the same mixture. The idea behind that guidance — that diesel fuel systems tolerate petrol by percentage — is wrong.
Myth: a newer diesel copes with a bit of petrol. If anything, the opposite. Protection matters more on newer diesels, not less, because their fuel passes through smaller parts at higher pressure.
"It starts, it drives, and so no harm done" — the myth that trips up more drivers than any other. A petrol engine fed diesel generally won't run, and so the driver stops and the harm stops with them. Whilst your pump grinds, a diesel fed petrol usually starts, idles and drives away as if nothing has happened. Being able to run is not proof of being fine.
An outdated fix for a distinct issue lies behind this one. Myth: "Add some two-stroke oil and drive the car home." None of what petrol thinned is put back by it — and afterwards, the tank still holds that petrol.
The next start sends petrol back round your pump from the lines and your filter, where some of it ends up once the engine has been run. That is why a DIY tank drain doesn't leave you sorted — a myth. Emptying petrol into a can at the roadside is also truly dangerous.
How does petrol in a diesel occur?
On purpose? Never. Through carelessness? Seldom, if ever. The forecourt makes it easy: the petrol nozzle is the smaller of the two, and it slips into a diesel filler with almost no resistance, whilst a diesel nozzle mostly won't go into a petrol vehicle at all. So the mistake runs one way.
Routine and your car falling out of step is how it occurs. A new vehicle, a hire car or a courtesy car. Two vehicles on one drive, one petrol, one diesel. A forecourt you know, only with its pumps laid out differently. Racing for a train outside Ivybridge and filling up en route. The first fill-up in a diesel Renault Clio after years of driving petrol is precisely the moment it takes place. Add a back seat full of children, a phone call or rain, and the hand wins.
Next time you fill up around Southville: preventing petrol in a diesel
- Not every forecourt in the UK keeps to green for unleaded and black for diesel, though most generally do. Read the petrol pump's label; the colour is just a clue.
- Plenty of motors state the fuel inside the filler flap or on the cap, so check there on the first fill in a car you do not know.
- Mark the key. In a house with one of each, a coloured fob or a sticker on the diesel's key does more than any amount of meaning to remember.
- 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 seems daft and it does the trick.
- Thinking about something else is when this becomes an easy mistake to make, so put the phone away then keep your mind on the pump.
- Some diesels have a filler built to reject a petrol nozzle, and devices you can add exist for cars without one. Such an inhibitor helps up to a point — as a safety net, not a reason to stop checking the petrol pump.
- Stop the moment you notice. Less petrol inside that tank makes a weaker mixture. It does not change what to do next, which is still not to start the car.
Petrol already in a diesel around Southville? Begin here
Then the order of things is brief. Don't switch your ignition on, and don't fire it up. The staff on the forecourt — whether at Asda Express itself or wherever you filled up — will usually help push it away from the pump if you ask. What was put in, about how much, and if it's run: tell us that when you ring 0333 366 0103.
Corrosion and deposits are the trouble with AdBlue, where petrol means lost protection. So if it was AdBlue, say so — and read its own Southville page.
Why one petrol in a diesel task around Southville costs more than another
Four separate jobs lie behind the four scenarios above — which is why there's no honest single price. The situation itself does most of the work of moving the cost. Two things follow that: the petrol that went in as a proportion of what the tank takes, then the spot your car is in and whether our van can reach it safely.
Ahead of any quote, not after, come three questions: your fuel that went in, its volume, and if it's run. That is why. A range becomes a straight figure when the answers are in.
About Southville
Southville is a small suburban area in Devon, situated inland at an elevation of 23 metres, and is located near Ticket Wood and West Charleton. Southville is characterized by its predominantly detached housing stock, reflecting the area's residential nature. Southville sits within the wider region of the South West, approximately 17.7 miles from Plymouth and 180.1 miles from London. Southville has a small population of around 537 residents.
Fuel drain cover around Southville and across Devon
Southville sits in the TQ postcode area, and our vans that answer petrol in diesel jobs there work the places around it as well — Ticket Wood, West Charleton and Kingsbridge among them. No need to move the car to us. Forecourts, supermarket car parks, lay-bys and your own drive are all locations where we work.
Southville: still at the pump?
The best place there is, then — that is where you are. Keep it off. Ring.