Maukinhill: Petrol in a Diesel Car? How Worried to Be
Probably less than you are now — provided nobody has started the car. Till the ignition primes the pump, your starter turns, or the car is driven, petrol in a diesel tank just rests there and does nothing. Which means the truthful reply to that first Maukinhill query — "have I wrecked it?" — usually no. Petrol in Diesel is who to call, with your engine kept off, so it stays that way. Read on for three things: the effect petrol has inside a diesel motor, the clues of how far it has spread, and the way to make sure you never repeat it.
Inside the motor: what petrol in a diesel really does
Passing through an engine, diesel does two jobs at once. Oiling comes before burning; it does both. The high-pressure pump and your injectors are designed to extremely fine gaps, and your diesel passing through them is what keeps those surfaces from wearing down against each other.
Petrol handles the first task 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 blend to wear itself. It is also made to resist igniting under compression — the opposite of what a diesel needs — which is why you get the rattling.
The shape of the issue is plain when you put those together. The harm is done by movement, not by contact. All a tank with petrol in it amounts to is a fuel fault. The beginning of a mechanical one is a pump that has been labouring on that petrol — and whatever a worn pump sheds moves on with the fuel to the injectors downstream.
Four scenarios we see around Maukinhill: how bad is petrol in a diesel?
The best case there can be: filled up, never started. On a forecourt, and truly only there, that petrol is still confined to the tank — since anywhere else the car was driven to get to it. The job is emptying and purging on the spot.
Started for a moment, or only the ignition on. The system has been primed, and so petrol has left your tank and got to your filter and the lines. Still usually easy: drain, flush, and the filter sorted.
Driven a few miles. Now the pump has spent those miles labouring on thinned fuel. The work is that tank, your lines, the fuel filter and fresh fuel through the whole system, and how hard the car was driven matters as much as how far. Driving the kids to the local primary school is one sort of trip. Any distance on the M8, under 10 miles from Maukinhill, means the engine working hard throughout, and a run to Glasgow, under 25 miles away, is a very different job too.
Driven till it protested. Knocking, a ragged idle, smoke, a throttle that has gone soft. The fuel is not behaving like diesel any more, and your motor is saying so. Stop wherever you are — the verge on Blairmore Road, a lay-by, a side street — and leave it where it is. The drain and flush-through still go first, and they take care of it: when a vehicle is stopped soon, permanent damage is very rare.
Maukinhill drivers and that petrol in a diesel myths they hear
Myth: "Fill it the rest of the way with diesel and it'll be fine." It will not. Nothing is removed by topping up — you're left with a fuller tank, still the same mixture. The idea behind that guidance — that diesel fuel systems tolerate petrol by percentage — is wrong.
"Newer diesels can handle a little petrol" — a myth, and closer to the opposite. Finer components and higher pressure are how a newer diesel runs its fuel, and that makes the protection matter more, not less.
This is the one that catches drivers. Myth: "If it starts and drives, there's no harm done." A petrol engine fed diesel normally will not run, and so the driver stops and the damage stops with them. Feed petrol to a diesel and it generally starts, idles and pulls away as if nothing has happened — all while its pump wears. Fine and running aren't the same at all.
Myth: "Add some two-stroke oil and drive the vehicle home." It's an outdated workaround for a separate problem. None of what petrol thinned is put back by it — and afterwards, that tank still holds that petrol.
"Drain it yourself and you are sorted" — a myth, because after it has been running some petrol lies in your filter and lines, ready to go right back through the pump at your next start. It is also genuinely hazardous to drain petrol into a can at the kerbside.
Petrol in a diesel: how does it occur?
On purpose? Never. Through carelessness? Rarely, if ever. One way only, since of the nozzles: the slimmer petrol one slips inside a diesel filler with almost no resistance, while the diesel one mostly won't fit a petrol vehicle. That is how the forecourt makes it simple.
When routine and the car stop matching, it happens. Courtesy car, hire car, or a car that is brand new. A household with one petrol and one diesel on the driveway. The pumps in a different order on a well-known forecourt. A hurried fill on the way to Whinhill with a train to catch. Precisely the moment it occurs: after years of driving petrol, a driver fills a diesel BMW 3 Series for the first time. With rain, a call coming in, or children to deal with, the hand simply does what it always has.
Avoiding petrol in a diesel next time you fill up around Maukinhill
- Not every forecourt in the UK follows green for unleaded and black for diesel, though most usually do. Check the petrol pump's label; the colour is only a hint.
- Inspect your filler flap. Many motors state the fuel type inside the flap or on the cap. Look at it on your first fill in any motor you do not know.
- One of each in the house? Label the key to your diesel — a bright fob, a sticker — because meaning to remember isn't enough.
- Before the nozzle comes off the petrol pump the first time you fill a hired or new motor, say "diesel" out loud. Silly, perhaps, yet it does the trick.
- Mistakes like this are easy to make while your mind is on something else, so your phone goes away.
- A misfuel inhibitor helps, up to a point. Some diesels have a filler designed to block a petrol nozzle, and add-on devices are available for vehicles without one. They are a safety net, not a reason to stop checking the pump.
- Spotting it mid-fill? Stop there and then. A weaker mix follows from less petrol in that tank, but your next step stays the same: don't fire it up.
Already put petrol in a diesel around Maukinhill?
Short and simple, then, is the order of things. Leave it unstarted, with the ignition switched off as well. Yet on the forecourt, at Morrisons or anywhere else? Ask the staff to help you push it clear of the petrol pump. Ring 0333 366 0103 next, with three answers — your fuel, the rough quantity, and if it has run.
AdBlue, not petrol? Then say so. Corrosion and deposits, not lost protection, make it a different problem — Maukinhill has a page just for it.
Maukinhill petrol in a diesel tasks: why one costs more than another
The four scenarios above are four separate tasks, so no single quote for this would be fair. What moves the cost is chiefly which of them you're in. Where your car is counts too, and whether a van can safely reach it, after the proportion of petrol to what that tank holds.
Three queries come first, before quoting, instead of after — what went in, how much, has it run — and that is the reason. Those replies change a range into a straight figure.
About Maukinhill and its setting
Maukinhill is a suburban area in Inverclyde, situated on the coast of Scotland, with a mix of semi-detached housing and other residential properties. Maukinhill sits at an elevation of 81 metres, overlooking the surrounding coastline and nearby communities such as Cartsdyke and Ladyburn. Maukinhill is located approximately 20 miles from Glasgow, making it a commuter-friendly location for those working in the city. Maukinhill has a population of around 4214 people, living in a variety of semi-detached homes.
Maukinhill and Inverclyde: where our fuel drain cover runs
Maukinhill rests in the PA postcode area, and the vans that answer petrol in diesel calls there work the locations around it as well — Cartsdyke, Ladyburn and Bridgend among them. A forecourt, a supermarket car park, a lay-by or your own drive are all locations we drain, and your car doesn't need to come to us.
In Maukinhill and still at the petrol pump?
The best place there is, then — that's where you are. Turned off it stays; then call.