Calderhall: Petrol in a Diesel Car? How Worried to Be
Unstarted? Then less worried than you probably feel. Until the ignition primes your pump, the starter turns, or the car is driven, petrol in a diesel tank simply rests there and does nothing. Which makes the honest reply to that first Calderhall query — "have I ruined it?" — usually no. Keep it that way: leave your motor off then ring Petrol in Diesel. Read on for three things: the effect petrol has inside a diesel motor, the signs of how far it has spread, and ways to make sure you never repeat it.
Inside the motor: what petrol in a diesel does
Diesel does two tasks on its way through a motor. Before it combusts, it lubricates — and then it burns. Built to extremely fine clearances, the fuel injectors and your pump depend on the diesel moving through them to keep their surfaces from wearing against one another.
Poorly at the first, not at all at the second: that is petrol. The rattling comes from petrol being made not to ignite when compressed, which is precisely the opposite of what a diesel needs. On top of that it is runnier than diesel, it strips away the protection the system hinges on, and any pump running on such a blend is wearing itself.
Together, those leave the shape of the trouble plain. The damage is done by movement, not by contact. Petrol in the tank is a fuel problem. The start of a mechanical problem is a pump that has been labouring on that petrol — and whatever a worn pump sheds moves on with your fuel to the injectors beyond it.
Calderhall, petrol in a diesel: four cases, from mild to serious
Fuelled but not once started — the best it gets. That petrol is inside your tank and just the tank, and the job is a drain and a flush where your car sits. This is the one situation that can only really occur at a forecourt, as anywhere else your car has been driven to get there.
A brief spell of running, or merely your ignition on. With the system primed, the lines and filter already hold petrol that has come from your tank. Usually little more than clearing, rinsing and sorting the fuel filter, and so still simple.
A few miles driven, and your pump has spent each of them working on weakened fuel. Tank, lines, filter, then clean fuel run through the whole system: that is the work, and the way the car was driven counts as much as the mileage. A school run to the local primary school is one thing. Any miles on the M8, under 3 miles from Calderhall, means the motor working hard throughout, and a run to Edinburgh, under 15 miles away, is a very different job as well.
Driven on until it protested — rattling, smoke, a lumpy idle, a dead throttle. What you are hearing is your engine signalling fuel that no longer runs like diesel. Whether it is the verge on Calderhall Crescent, a lay-by or a side street, stop there then leave it. What comes first is still the drain and flush, and that takes care of it, with lasting damage very rare if a car is pulled over soon.
Petrol in a diesel stories Calderhall drivers hear
Myth: "Fill it the rest of the way with diesel and it will be fine." It will not. Topping up removes nothing; it gives you a fuller tank of the same mix. That advice assumes a diesel fuel system tolerates petrol by percentage. It does not.
Not so: a current diesel copes with a bit of petrol. If anything, the opposite. At higher pressure, through finer components: that's how a modern diesel moves its fuel, and so the protection counts for more, not less.
Myth: "If it starts and drives, there's no harm done." This is the one that fools drivers. Diesel in a petrol motor normally leaves a motor that won't run: the motorist stops, and so does the damage. Feed petrol to a diesel and it usually starts, idles and drives away like nothing happened — all while its pump wears. Being able to run isn't the same as being fine.
Myth: "Add some two-stroke oil and drive the car home." It is an old workaround for a distinct problem. What petrol has weakened stays thinned, and that petrol stays inside your tank anyway.
"Drain it yourself and you're sorted" — a myth, since after it has been running some petrol lies in the filter and lines, ready to go right back through your pump on your next start. On top of that, petrol drained into a can by the road is truly dangerous.
Why petrol in a diesel occurs so easily
It is seldom carelessness, and nobody does it on purpose. One way only, since of the nozzles: the narrower petrol one slides inside a diesel filler with almost no resistance, while the diesel one generally won't fit a petrol vehicle. That's how the forecourt makes it easy.
It happens when habit and your car stop matching. Courtesy car, hire car, or a car that's brand new. A household with one petrol and one diesel on the driveway. A forecourt you know, but with its pumps arranged differently. A rushed fill on the way to Kirknewton with a train to catch. A new-to-you diesel Renault Megane, its first fuelling, and a motorist used to petrol: exactly when it occurs. With rain, a call coming in, or children to deal with, your hand simply does what it has always done.
Next time you fill up around Calderhall: preventing petrol in a diesel
- The label is what matters, so read the petrol pump rather than the colour: in the UK unleaded handles are usually green and diesel black, but not on each forecourt.
- In a car you don't know, look inside the flap over your filler or at the cap before your first fill: many vehicles print the fuel type there.
- 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 label it.
- Before the nozzle comes off the pump the first time you fuel a hired or new motor, say "diesel" aloud. Daft, perhaps, yet it does the trick.
- Mistakes like this are straightforward to make while your mind is on something else, so your phone goes away.
- A misfuel inhibitor helps, up to a point. Some diesels come with a filler designed to reject a petrol nozzle, and add-on devices exist for cars without one. They are a safety net, not a reason to stop checking the pump.
- Stop the moment you realise. Less petrol inside your tank means a weaker blend. It does not change what to do next, which is still not to crank it.
Put petrol in a diesel around Calderhall already?
In that case, there's just a short order of things. Never crank it, and do not turn the ignition on. Ask the staff to help you push it clear of the pump if you are still at the forecourt, whether that is Shell or anywhere else. What was put in, roughly how much, and if it's run: tell us that when you call 0333 366 0103.
AdBlue, not petrol? Then say so. Corrosion and deposits, not lost lubrication, make it a separate problem — Calderhall has a page all for it.
Why one petrol in a diesel job around Calderhall costs more than another
The four scenarios above are four separate jobs, so no single price for this would be honest. What shifts your cost is chiefly which of them you are in. After that it's the share — how much petrol got in against how much your tank holds — and after that where the vehicle is and whether our van can get to it safely.
That is why our engineers ask three queries before costing rather than after: what went in, how much, and whether it has run. Those answers turn a range into a straight figure.
About Calderhall, for a moment
Calderhall is a suburban area situated on the riverside in West Lothian, with a mix of semi-detached housing and a population of around 4042 residents. Calderhall sits at an elevation of 127 metres, close to nearby places such as Langton, East Calder, and Oakbank. Calderhall is located near Edinburgh, Scotland's capital city, which is approximately 11.5 miles away. Calderhall is also relatively distant from London, at a distance of around 332 miles.
Calderhall and West Lothian: where our fuel drain cover reaches
Petrol in diesel call-outs around Calderhall — part of the EH postcode area — go to teams that likewise cover the locations around it, Langton, East Calder and Oakbank among them. You need not move the vehicle to us. Forecourts, supermarket car parks, lay-bys and your own driveway are all locations where we work.
At the petrol pump in Calderhall, right now?
The best position there is, then — that's where you are. Keep it off. Phone.