Wardie: Petrol in a Diesel Car? How Worried to Be
If it hasn't been started, you can worry less than you likely are. Everyone in Wardie begins with "have I ruined it?", and the fair answer is normally no: petrol resting in your tank of any diesel remains harmless till priming, cranking or driving draws it into the fuel system. Petrol in Diesel is who to call, with the engine kept off, and so it stays that way. Further down, this page sets out what petrol really does inside a diesel, how far it might have gone, and how to stop it happening to you again.
The engine and petrol in a diesel: what happens
Two tasks fall to diesel on its journey round a motor. Lubricating comes before burning; it does both. Built to extremely fine clearances, your injectors and your pump depend on your diesel flowing through them to keep their surfaces from wearing against one another.
Of those two jobs, petrol manages the first badly and the second not at all. Being less viscous than diesel, petrol strips out the lubrication a fuel system needs, leaving a pump on the mixture to wear itself. It's equally made to resist igniting under compression — the opposite of what a diesel needs — which is why you hear the knocking.
Taken together, they make clear the shape the problem takes. Contact doesn't do the damage — circulation does. A tank with petrol in it is a fuel fault. Whatever a worn pump sheds goes on, carried by the fuel, into the fuel injectors further along, which is why a pump that has worked on that petrol is where a mechanical issue begins.
Petrol in a diesel around Wardie: how bad is it? Four cases
The best case there can be: filled up, never started. Being at a forecourt is what makes this possible: elsewhere, your car has been driven there to begin with. With that petrol held inside your tank alone, it's emptied and rinsed on the spot, and nothing more is needed.
Ignition on, or started for a second. The fuel system has been bled, and so petrol has left that tank and got to your filter and your lines. Still usually easy: drain, flush, and your filter seen to.
Driven a few miles. Now the pump has spent these miles labouring on diluted fuel. The work is the tank, your lines, the filter and fresh fuel through the entire circuit, and how hard the car was driven counts as much as how far. On the school run to the local primary school, the mileage is short. Getting as far as Edinburgh, under 3 miles away, makes a very different task — as does any mileage on the M8, under 5 miles from Wardie, with your engine labouring hard the whole time.
Knocking, a lumpy idle, smoke, a throttle gone soft: driven till it complained. What you are hearing is the motor reporting fuel that no longer acts like diesel. Pull up wherever you are — the verge on Boswall Terrace, a lay-by, a side street — then leave the vehicle there. A vehicle pulled over early very seldom has lasting damage, because the drain and the flush, which still come first, take care of it.
Myths Wardie drivers hear about petrol in a diesel
"Top it up the rest of the way with diesel and it'll be fine" — a myth. It won't. Nothing is removed when you top up — the tank simply holds more of the same blend. A diesel fuel system doesn't accept petrol by percentage in the way that guidance supposes.
Myth: "A modern diesel can cope with a bit of petrol." If anything, the opposite. At higher pressure, through more precise components: that is how a modern diesel handles its fuel, so the protection matters for more, not less.
Myth: "If it starts and drives, there is no damage done." This is the one that fools motorists. Feed diesel to a petrol engine and it usually won't run, so the motorist stops — and the harm stops with them. Feed petrol to a diesel and it normally fires up, idles and pulls away as if nothing has happened — all while its pump is wearing. A running engine doesn't mean fine.
An old workaround for a separate issue is behind this one. Myth: "Add some two-stroke oil and drive the vehicle home." None of what petrol weakened is put back by it — and afterwards, that tank still contains that petrol.
Myth: "Drain that tank yourself and you are sorted." After the engine has been run, some of that petrol is no longer inside the tank: it's in the filter and your lines, and it goes right back through the pump on the next start. It's also truly risky to drain petrol into a can at the roadside.
How petrol ends up: petrol in a diesel
A careless moment is seldom the cause, and nobody means to do it. One way only, because of the nozzles: the narrower petrol one slides inside a diesel filler with almost no resistance, while the diesel one mostly will not fit a petrol motor. That is how the forecourt makes it easy.
It occurs when habit and your car stop matching. A new car, a hire car or a courtesy car. One petrol and one diesel on the driveway of the same household. Your ordinary forecourt, its pumps now in a different order. Racing for a train outside Edinburgh Waverley and fuelling up en route. Exactly the moment it occurs: after years of driving petrol, a driver fills a diesel Volkswagen Golf 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.
Wardie drivers: how to avoid petrol in a diesel next time
- A green handle 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. Plenty of cars state the fuel inside the flap or on the cap. Look at it on the first fill in any motor you do not know.
- Good intentions count for less than a sticker or a fob in a vivid colour on the diesel's key if a house has one of each. So mark it.
- "Diesel", out loud, before you lift the nozzle — every time a new or hired car gets its first tank. It sounds silly. It does the trick.
- Tuck the phone away. This is an easy mistake to make whilst you are thinking about something else.
- Up to a point, a misfuel inhibitor helps: some diesels come with a filler built to reject a petrol nozzle, and aftermarket devices exist for the remainder. Treat it as a backstop, and keep checking the pump.
- Less petrol makes a thinner mix, and so stop as soon as you realise — while remembering that your next stage is unchanged. It is still not to start the car.
Already put petrol in a diesel around Wardie?
The order of things is brief, then. Never fire it up, and do not switch the ignition on. If you are still at the forecourt — Morrisons or anywhere else — ask the attendants to help you push the vehicle away from the petrol pump. Then ring 0333 366 0103 and tell us what was put in, roughly how much, and if it has run.
If it was AdBlue rather than petrol, say so. That is a different problem — corrosion and deposits instead of lost lubrication — and it has its own page for Wardie.
Wardie petrol in a diesel tasks: why one costs more than another
The four situations above are four separate jobs, so no single price for this would be honest. What moves your cost is chiefly which of them you're in. Where the vehicle is matters too, and whether our van can safely get to it, after the share of petrol to what your tank holds.
Three questions come first, before quoting, rather than after — what got in, how much, has it run — and this is the reason. Their answers are what change a range into one firm number.
About Wardie and where it is
Wardie is a coastal suburban area in the City of Edinburgh, situated approximately 2 miles from Edinburgh city centre. Wardie occupies a relatively low-lying area, with an elevation of around 28 metres, and is characterised by predominantly flat-type housing. Wardie is close to nearby places such as Pilton, Granton, and Inverleith, and is part of the larger Edinburgh urban area. Wardie has a population of around 9951 residents.
Fuel drain cover around Wardie and across City of Edinburgh
Our vans answering petrol in diesel call-outs around Wardie, in the EH postcode area, equally work the spots around it, Pilton, Granton and Inverleith included. Our engineers drain wherever the car is — your own drive, a lay-by, a supermarket car park, a forecourt — so it never needs to come to us.
Wardie: still at the petrol pump?
In that case, you could not be in a better position. Turned off it remains; then call.