Highfields Caldecote: Petrol in a Diesel Car? How Worried to Be
Far less than you likely are, if it hasn't been started. Petrol resting in a diesel tank does nothing to the engine until something draws it through your fuel system — the ignition priming your pump, your starter, or the drive on its own. So the truthful answer to the first query everyone in Highfields Caldecote asks, "have I ruined it?", is usually no. Keep it that way: leave the engine off and call Petrol in Diesel. The rest of this page explains what petrol actually does to a diesel, how to tell how far it has got, and how to make sure it doesn't happen to you again.
Your engine and petrol in a diesel: what happens
On its way through a motor, diesel has two tasks. Lubricating comes before burning; it does both. Built to extremely fine clearances, the injectors and the pump rely 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. It's thinner than diesel and strips away the lubrication the fuel system rests on, so a pump running on a petrol mix 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's where the rattling comes from.
Together, those leave the shape of the issue clear. Not contact but movement is what does the harm. Petrol in a tank is a fuel problem. Whatever a worn pump sheds travels on, carried by the fuel, into your injectors further along, which is why a pump that has been working on the petrol is where a mechanical problem begins.
Four scenarios our engineers see around Highfields Caldecote: how bad is petrol in a diesel?
Fuelled but not once started — the best it gets. That petrol is in the tank and only that tank, and the job is a drain and a flush where the vehicle stands. This is the one situation that can only truly occur on a forecourt, as anywhere else your car has been driven to get there.
A brief spell of running, or just your ignition on. Petrol has left that tank and reached the fuel filter and the fuel lines, since the fuel system has been primed. That's usually still an easy job — a drain, a flush, and the filter dealt with.
Those few miles on the road were the pump labouring on fuel weakened by petrol the whole way. How hard your car was driven matters as much as how far, and this work covers your tank, your lines, the filter and fresh fuel through the entire circuit. On the school run to Caldecote Primary School, the distance is small. Any distance on the M11, under 5 miles from Highfields Caldecote, means your engine has worked hard throughout, and a run to Cambridge, under 10 miles away, is a very different task as well.
Driven until it complained. Rattling, a ragged idle, smoke, a throttle that has gone soft. What you are hearing is the engine reporting fuel that no longer runs like diesel. Whether it is the verge on Bosserts Way, a lay-by or a side road, stop there and leave it. Long-term damage is very unusual if a vehicle is pulled over quickly, and the fuel drain and flush that still come first take care of it.
Myths Highfields Caldecote people hear about petrol in a diesel
Myth: "Fill it the rest of the way with diesel and it will be fine." It will not. Nothing is removed when you top up — that tank just holds more of the same mixture. Percentage isn't how a diesel fuel system tolerates petrol, however much that advice presumes.
Myth: "A modern diesel can cope with a bit of petrol." If anything, the opposite. A current diesel sends its fuel through smaller parts at higher pressure, which makes the lubrication matter more, not less.
Myth: "If it starts and drives, there is no damage done." This is the one that catches people. A petrol motor fed diesel generally will not run, and so the motorist stops and the damage stops with them. Feed petrol to a diesel and it usually starts, ticks over and drives away like nothing has happened — all while its pump wears. Fine and running are not the same at all.
Myth: a two-stroke additive makes it safe to drive home. It was an old workaround, meant for another problem. It does not put back what petrol has weakened, and the petrol is still in that tank afterwards.
Myth: "Drain your tank yourself and you're sorted." Once your engine has run, some of that petrol is no longer in the tank: it is in the filter and the lines, and it goes right back through the pump at the next start. It is also genuinely dangerous to drain petrol into a can at the kerbside.
How petrol ends up: petrol in a diesel
No one does it on purpose, and it's rarely carelessness. The forecourt makes it simple: the petrol nozzle is the narrower of the two, and it slips into a diesel filler with almost no resistance, while a diesel nozzle mostly won't go into a petrol car at all. So the mistake runs one way.
When routine and the car stop matching, it occurs. Hire cars, courtesy cars, and vehicles that are new to you. Households running one of each, petrol and diesel. A forecourt you know, only with its pumps laid out differently. Racing for a train at Cambridge and filling up en route. The first fill-up in a diesel Volkswagen Tiguan after years of driving petrol is exactly the moment it happens. Throw in a back seat full of kids, a phone call or rain, and habit wins.
How to avoid petrol in a diesel on your next fill-up in Highfields Caldecote
- Not every forecourt in the UK follows green for unleaded and black for diesel, even if most usually do. Check the petrol pump's label; the colour is just a clue.
- Plenty of vehicles state the fuel type inside your filler flap or on the cap, and so check there on the first fill in a car you do not know.
- Mark your key. In a home with one of each, a coloured fob or a sticker on the diesel's key does more than any amount of meaning to remember.
- Before the nozzle leaves the petrol pump the first time you fill a hired or new car, say "diesel" out loud. Daft, perhaps, but it does the trick.
- Thinking about something else is when this becomes an easy mistake to make, and so tuck the phone away then keep your mind on the petrol pump.
- A misfuel inhibitor helps, up to a point. Some diesels come with a filler designed to refuse a petrol nozzle, and add-on devices are available for cars without one. They are a backstop, not a reason to stop reading the pump.
- As soon as you notice, stop: less petrol inside that tank makes a weaker blend. What to do next does not change, though — still don't start the car.
Already put petrol in a diesel around Highfields Caldecote?
The order of things is short, then. Never start the car, and don't switch the ignition on. If you're still on the forecourt — BP or anywhere else — ask the staff to help you push the vehicle away from the pump. Phone 0333 366 0103 next, with three facts — your fuel, the approximate amount, and whether it's run.
Corrosion and deposits form the issue with AdBlue, whereas petrol means lost lubrication. So if it was AdBlue, say so — and read its own Highfields Caldecote page.
Why one petrol in a diesel task around Highfields Caldecote costs more than another
A fair single quote does not exist here: four situations, four separate jobs. Mostly, your cost shifts with which one you're in. Next it's the ratio — how much petrol went in against how much that tank holds — and after that where the vehicle is and whether a technician can get to it safely.
Before any quote, not after, come three questions: the fuel that was put in, the amount, and if it has run. That's why. Their replies are what turn a range into one firm number.
About Highfields Caldecote
Highfields Caldecote is a village in Cambridgeshire, situated approximately 6 miles from Cambridge and 48.8 miles from London. Highfields Caldecote sits in a rural area at an elevation of around 73 metres, with nearby places including Childerley Gate and Upper Cambourne. Highfields Caldecote has a population of around 927 people, predominantly living in detached houses.
Fuel drain cover across Cambridgeshire, Highfields Caldecote included
Our teams answering petrol in diesel call-outs around Highfields Caldecote, in the CB postcode area, equally work the places near it, Childerley Gate, Caldecote and Upper Cambourne included. Our engineers 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.
At the pump in Highfields Caldecote, still?
Then, you could not be in a better place. Ring, and leave it switched off.