Blantyre: Petrol in a Diesel Car? How Worried to Be
Provided it has not been started, worry far less than you probably are. Everyone in Blantyre starts with "have I ruined it?", and the honest answer is usually no: petrol resting inside the tank of a diesel stays harmless till priming, cranking or driving pulls it into your fuel system. To leave it that way, phone Petrol in Diesel then leave your motor switched off. What petrol actually does to a diesel, how to gauge how far it has travelled, and how to stop it from happening again: that's the remainder of this page.
Inside your engine: what petrol in a diesel does
Two tasks fall to diesel on its journey through a motor. It protects first, and after that does it burn. Made to very fine clearances, the injectors and the pump depend on your diesel flowing through them to stop their surfaces wearing against one another.
The second task petrol does not do at all, and the first it does poorly. The clattering comes from petrol being designed not to ignite when compressed, which is precisely the opposite of what a diesel needs. On top of that it is thinner than diesel, it strips out the protection the system rests on, and any pump running on that mixture is wearing itself.
Combined, those leave the shape of the problem clear. Not contact but movement is what does the harm. Any tank with petrol in it is a fuel issue. A pump that has been running on that petrol is the beginning of a mechanical one, and whatever a worn pump sheds moves on with your fuel to your injectors further on.
How serious is petrol in a diesel? Four scenarios our technicians see around Blantyre
Filled up, and not started: no case is better. Just your tank has petrol in it, so the task is emptying that tank and flushing the system where the car stands. This scenario can only truly take place at a forecourt: anywhere else, your car got there by being driven.
Your ignition turned on, or a short start. With your system primed, the lines and filter now hold petrol that has come from your tank. That's usually still an easy task — a drain, a flush, and the fuel filter seen to.
A couple of miles driven, and your pump has spent each of them labouring on thinned fuel. Tank, lines, filter, then clean fuel run through the whole circuit: that is this work, and the way your car was driven matters as much as the miles. A school run to the local primary school is one thing. Getting as far as Glasgow, under 10 miles away, makes a very different job — as does any mileage on the M74, under 3 miles from Blantyre, with the motor running hard the whole time.
Knocking, an uneven idle, smoke, a throttle gone soft: driven till it complained. What you are hearing is your engine reporting fuel that no longer acts like diesel. Whether it's the verge on A724, a lay-by or a side road, stop there then leave it. A car stopped early very rarely has lasting damage, as the fuel drain and the flush, which still go first, sort it out.
Petrol in a diesel myths Blantyre people hear
Myth: "Fill it the rest of the way with diesel and it'll be fine." It will not. Topping up takes out nothing; it gives you a fuller tank of the same mixture. Percentage is not how a diesel fuel system copes with petrol, whatever that advice presumes.
Myth: a modern diesel copes with a bit of petrol. Rather, the opposite. Smaller parts and higher pressure are the way a newer diesel runs its fuel, and that makes the protection matter more, not less.
The myth that catches drivers out: if it starts and drives, it must be unharmed. Feed diesel to a petrol engine and it usually won't run, so the driver stops — and the damage stops with them. Nothing seems to have happened when a diesel fed petrol fires up, ticks over and drives away, as it usually does; meanwhile your pump grinds. Fine and running aren't the same thing.
Myth: "Add some two-stroke oil and drive it home." It is an old workaround for a distinct fault. None of what petrol diluted is put back by it — and afterwards, your tank still contains the petrol.
Myth: "Drain the tank yourself and you're sorted." Once your engine has been run, some of that petrol is no longer in the tank: it's in the filter and the fuel lines, and it goes straight back through the pump on your next start. Draining petrol into a can at the roadside is also genuinely risky.
How petrol ends up: petrol in a diesel
It is rarely carelessness, and nobody does it on purpose. The petrol nozzle is the narrower 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 slip runs one way.
Habit and the vehicle getting out of step is how it occurs. A vehicle that's new to you — hired, on loan as a courtesy car, or just bought. A household with one petrol and one diesel on the driveway. The pumps in a different order on a familiar forecourt. Filling up in a hurry on the way to the nearest station, with a train to catch. The first fill-up in a diesel Volkswagen Passat after years of driving petrol is precisely the moment it occurs. With rain, a call coming in, or children to deal with, your hand just does what it has always done.
Next time you fill up in Blantyre: preventing petrol in a diesel
- Read the petrol pump, not the colour. In the UK unleaded handles are usually green and diesel black, yet not on every forecourt. The label is what matters.
- The first fill in a new car is the time to check the filler flap — on it, or on the cap, plenty of motors state the fuel to use.
- Label your key. In a home with one of each, a coloured fob or a sticker on your diesel's key does more than any amount of meaning to remember.
- Before the nozzle comes off the pump the first time you fill a hired or new car, say "diesel" aloud. Daft, perhaps, but it does the trick.
- Thinking about something else is when this becomes an easy mistake to make, so put your phone away and keep your mind on the petrol pump.
- Up to a point, a misfuel inhibitor helps: some diesels come with a filler designed to block a petrol nozzle, and aftermarket devices exist for the remainder. Treat it as a backstop, then keep checking the petrol pump.
- Stop the moment you notice. Less petrol in that 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 in Blantyre already?
The order of things is short, then. Do not fire it up, and do not turn your ignition on. The staff at the forecourt — whether at Asda itself or wherever you filled up — will normally help roll it away from the pump if you ask. Phone 0333 366 0103 next, with three answers — your fuel, the rough amount, and if it has run.
If it was AdBlue rather than petrol, say so. That's a different issue — corrosion and deposits and not lost lubrication — and it has its own page for Blantyre.
Blantyre petrol in a diesel tasks: why one costs more than another
The four situations above are four separate tasks, so no single quote for this would be honest. Which of them you are in is mostly what shifts your cost. Where the vehicle is matters too, and whether a technician can safely reach it, after the proportion of petrol to what your tank takes.
Three queries come first, before quoting, rather than after — what was put in, how much, has it run — and that is the reason. The replies change a range into a straight figure.
About Blantyre itself
Blantyre is a riverside locality in South Lanarkshire, situated near the city of Glasgow. Blantyre sits at an elevation of 61 metres, close to the River Clyde, and is part of the greater Glasgow urban area. Blantyre has a mix of housing types, with flats being the predominant form of accommodation, and is located near other nearby places such as Low Blantyre and Auchinraith.
Fuel drain cover around Blantyre and across South Lanarkshire
The teams answering petrol in diesel call-outs around Blantyre, in the G postcode area, also work the spots near it, Low Blantyre, Low Blantrye and Auchinraith among them. The car doesn't need to come to us: we drain at a forecourt, in a supermarket car park, in a lay-by or on your own driveway.
At the petrol pump in Blantyre, right now?
The best place there is, then — that is where you are. Call, and leave it turned off.