Denmore: Petrol in a Diesel Car? How Worried to Be
Less than you likely are, if it has not been started. "Have I ruined it?" is the first question anyone in Denmore asks, and the honest answer is normally no, since petrol left in a diesel tank hurts nothing till it's dragged through the system — by ignition priming, by your starter, or by being driven. Keep it like that: leave the engine off then ring Petrol in Diesel. The remainder of this page covers what petrol really does to a diesel, how to tell how far it has got, and how to make sure it doesn't happen to you again.
What petrol in a diesel does to the motor
On its way through an engine, diesel has two jobs. Before it ignites, it protects — then it burns. The high-pressure pump and the injectors are made to very fine clearances, and your diesel passing through them is what keeps those surfaces from wearing against one another.
Poorly at the first, not at all at the second: that is petrol. It's runnier than diesel and strips away the lubrication the fuel system depends on, so a pump running on a petrol blend is a pump wearing itself. And petrol is designed to resist igniting under compression, which is the reverse of what a diesel needs from its fuel. That is where the rattling comes from.
Seen together, they show what shape the trouble takes. Not contact but circulation is what does the damage. Where that petrol is only in the tank, it's a fault of fuel, nothing more. The beginning of a mechanical problem is a pump that has been labouring on that petrol — and whatever a worn pump sheds moves on with the fuel to the fuel injectors downstream.
Denmore, petrol in a diesel: four situations, from mild to significant
Filled up, and not started: nothing beats it. Only that tank has petrol in it, and so the task is draining that tank and purging the system where the car stands. This scenario can only truly occur at a forecourt: anywhere else, the car got there by being driven.
The ignition switched on, or a brief start. Petrol has come out of that tank and got to your filter and your lines, because the system has been primed. Drain, flush, see to the filter: still normally straightforward.
Those few miles on the road meant your pump labouring on fuel diluted by petrol throughout. Mileage is only half of that; how hard it was driven matters just as much. Either way this work runs to the tank, the lines, the fuel filter and fresh fuel through the entire circuit. On the school run to the local primary school, the distance is small. Driving as far as Aberdeen, under 5 miles away, makes a very different task — as does any miles on the M90, over 50 miles from Denmore, with the engine working hard the whole time.
Driven on till it protested — knocking, smoke, a lumpy idle, a dead throttle. What you are hearing is your engine signalling fuel that no longer acts like diesel. Leave it wherever it stops: a lay-by, a quiet street, the verge on Denmore Place. What goes first is still the fuel drain and flush-through, and that sorts it out, with permanent damage very uncommon when a vehicle is pulled over quickly.
Stories Denmore drivers hear about petrol in a diesel
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 bigger tank of the same mixture. A diesel fuel system doesn't tolerate petrol by percentage in the way that advice supposes.
Myth: "A newer diesel can cope with a bit of petrol." If anything, the reverse. Finer parts and higher pressure are how a current diesel runs its fuel, and that makes the protection matter more, not less.
One myth that catches motorists off guard: if it starts and drives, it must be unharmed. Feed diesel to a petrol engine and it usually will not run, and so the motorist stops — and the damage stops with them. Feed petrol to a diesel and it generally starts, ticks over and drives away like nothing has happened — all the while its pump wears. Running isn't the same as fine.
Myth: "Add some two-stroke oil and drive the car home." It's an outdated fix for a separate issue. The petrol is still in your tank after that, and what it has thinned isn't put back.
Myth: "Drain that tank yourself and you are sorted." Once your engine has run, some of the petrol is no longer inside the tank: it's in the fuel filter and the fuel lines, and it goes right back through your pump at your next start. It's also really risky to drain petrol into a can at the roadside.
Why petrol in a diesel occurs so easily
A careless moment is rarely the cause, and nobody means to do it. The petrol nozzle is the smaller of the two and slips into a diesel filler with almost no resistance; a diesel nozzle generally will not go into a petrol vehicle at all. The forecourt makes it simple, and the slip runs one way.
When habit and the car stop matching, it takes place. A new vehicle, a hire car or a courtesy car. Two motors on one driveway, one petrol, one diesel. A forecourt you know, only with its pumps arranged differently. A train to catch, and a rushed fill on the way to Aberdeen. Precisely the moment it occurs: after years of driving petrol, someone fills a diesel Volkswagen Golf for the first time. Throw in a back seat full of children, a phone call or rain, and the hand takes over.
Denmore motorists: how to prevent petrol in a diesel next time
- Not every forecourt in the UK keeps to green for unleaded and black for diesel, even if most usually do. Read the pump's label; the colour is only a hint.
- In a car you do not know, look inside the flap over the filler or at the cap before your first fill: plenty of vehicles print the fuel type there.
- Good intentions count for less than a sticker or a fob in a vivid colour on your diesel's key when a home has one of each. So mark it.
- Before the nozzle leaves the pump the first time you fuel a hired or new motor, say "diesel" aloud. Silly, yes, yet it works.
- Mistakes like this are simple to make while your mind is on something else, so the phone goes away.
- Some diesels come with a filler designed to refuse a petrol nozzle, and devices you can add exist for vehicles without one. Such an inhibitor helps up to a point — as a backstop, not a reason to stop checking the pump.
- Less petrol makes a thinner blend, so stop the moment you notice — though remembering that the next stage is unchanged. It is still not to fire it up.
Put petrol in a diesel in Denmore already?
The order of things is brief, then. Starting it is out, and so is switching on the ignition. Yet on the forecourt, at Esso or anywhere else? Ask the attendants to help you roll it away from the petrol pump. What was put in, roughly how much, and if it's run: tell us that when you phone 0333 366 0103.
If it was AdBlue rather than petrol, say so. That's a different fault — corrosion and deposits instead of lost protection — and it has its own page for Denmore.
One petrol in a diesel job around Denmore costs more than another. Why?
The four scenarios above are four separate tasks, so no single quote for this would be fair. What moves your cost is chiefly which of them you're in. Where the car is counts too, and whether our van can safely reach it, after the proportion of petrol to what your tank takes.
What was put in, how much, and if it has run — three questions we ask before costing, not after, for exactly that reason. The replies turn a range into a straight figure.
About Denmore, for a moment
Denmore is a suburban area located on the coast in Aberdeen City, Scotland, with an elevation of around 40 metres. Denmore sits approximately 3.2 miles from Aberdeen city centre and is near other local places such as Bridge of Don and Middleton Park. Denmore has a population of around 2325 people and predominantly consists of semi-detached housing. Denmore is part of the larger Aberdeen urban area, which is situated about 400.9 miles from London.
Fuel drain cover across Aberdeen City, Denmore included
Bridge of Don, Middleton Park and Blackdog are among the locations near Denmore that the same vans work, answering petrol in diesel jobs across Denmore's AB postcode area. We drain where the vehicle is — your own driveway, a lay-by, a supermarket car park, a forecourt — so it never needs to come to us.
Still at the pump around Denmore?
Then you're in the best spot there can be. Switched off it remains; then call.