Petrol in a Diesel Car in Coryton: How Worried Should You Be?
Provided it hasn't been started, worry far less than you likely are. Till your ignition primes your pump, the starter cranks, or the vehicle is driven, petrol in a diesel tank just waits there and does no harm. Which means the truthful reply to that first Coryton question — "have I ruined it?" — usually no. Petrol in Diesel is who to call, with the engine kept off, so it stays that way. The rest of this page covers 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.
Petrol in a diesel: what does it do to the engine?
On its way through an engine, diesel does two jobs. Before it ignites, it lubricates — and then it ignites. What stops the surfaces inside the high-pressure pump and the fuel injectors from grinding against one another is your diesel passing through them — they are made to extremely fine clearances.
Badly at the first, not at all at the second: that is petrol. Being less viscous than diesel, petrol strips away the protection a fuel system needs, so a pump running on the blend to wear itself. It's equally made to resist igniting under compression — the reverse of what a diesel needs — which is why you hear the clattering.
Put these together and the shape of the trouble is clear. The harm is done by movement, not by contact. Where that petrol is only inside that tank, it is a problem of fuel, nothing more. A pump that has been running on that petrol is the start of a mechanical one, and whatever a worn pump sheds moves on with your fuel to the injectors downstream.
Petrol in a diesel around Coryton: how bad is it? Four situations
Filled up, and not started: nothing beats it. Only the tank has petrol in it, so the task is clearing the tank and flushing the fuel system where your car sits. This scenario can only really occur on a forecourt: anywhere else, your car got there by being driven.
A moment's running, or merely the ignition on. Once primed, the fuel system has pulled petrol out of that tank up to the fuel filter and the fuel lines. That's generally still a straightforward job — a drain, a flush, and your filter dealt with.
A couple of miles driven, and your pump has spent every one of them running on thinned fuel. How hard your car was driven counts as much as how far, and the work covers the tank, the lines, the fuel filter and fresh fuel through the whole circuit. On the school run to the local primary school, the miles is small. Any mileage on the M4, under a mile from Coryton, means the motor working hard throughout, and a run to Cardiff, under 5 miles away, is a very different task too.
It protested, and only then stopped: smoke, knocking, a throttle gone soft, an idle gone ragged. The engine is telling you the fuel is no longer acting like diesel. Pull up on the spot — on the verge on Coryton Rise, at the kerb, down a side road — and do not move it. The fuel drain and flush-through still come first, and they deal with it: when a car is pulled over early, lasting damage is very uncommon.
Coryton drivers and the petrol in a diesel stories they hear
It will not be fine. The myth: "Fill it the rest of the way with diesel and it'll be." A bigger tank of the same mix is all you get, because topping up takes out nothing. That advice presumes a diesel fuel system handles petrol by percentage. It does not.
Not so: a modern diesel copes with a bit of petrol. If anything, the reverse. A current diesel sends its fuel through more precise parts at higher pressure, which makes the lubrication count more, not less.
The myth that catches motorists out: if it starts and drives, it must be unharmed. Any petrol motor fed diesel usually won't run, and so the driver stops and the damage stops with them. Feed petrol to a diesel and it usually fires up, ticks over and drives away like nothing has happened — all the while its pump wears. Running is not the same as fine.
Not so: a two-stroke additive makes it safe to drive home. It is an old fix, meant for another issue. None of what petrol thinned is put back by it — and afterwards, that tank still holds the petrol.
The next start draws petrol back round your pump from the fuel lines and the filter, where some of it sits once the motor has been run. That is why draining your tank yourself does not leave you sorted — a myth. On top of that, petrol drained into a can by the road is truly dangerous.
Why petrol in a diesel occurs so easily
No one does it on purpose, and it's seldom carelessness. The petrol nozzle is the smaller of the two and slides into a diesel filler with almost no resistance; a diesel nozzle mostly will not go into a petrol vehicle at all. The forecourt makes it simple, and the mistake runs one way.
It occurs when habit and the vehicle stop matching. A new motor, a hire car or a courtesy car. A household with one petrol and one diesel on the driveway. A familiar forecourt with the pumps in a different order. A hurried fill en route to the nearest station with a train to catch. The first fill-up in a diesel Renault Megane after years of driving petrol is precisely the moment it takes place. With rain, a call coming in, or a car full of children to deal with, the hand simply does what it always has.
Avoiding petrol in a diesel next time you fill up around Coryton
- The label is what matters, and so check the petrol pump instead of the colour: in the UK unleaded handles are normally green and diesel black, but not on each forecourt.
- Check the filler flap. Plenty of motors state the fuel type inside the flap or on the cap. Look at it on the first fill in a motor you don't know.
- A coloured fob or a sticker on your diesel's key does more than any amount of meaning to remember, for a home with one of each.
- "Diesel", out loud, before you pick up the nozzle — each time a new or hired car gets its first tank. It seems daft. It works.
- Put your phone away. This is an easy mistake to make whilst you are thinking about something else.
- Add-on devices are available for motors without one, and some diesels are built with a filler that will not accept a petrol nozzle. Useful — but a safety net at best, never a reason to stop checking the label.
- Stop as soon as you realise. Less petrol in that tank makes a thinner mixture. It doesn't change what to do next, which is still not to crank it.
Petrol already in a diesel around Coryton? Begin here
Short and simple, then, is the order of things. Don't turn your ignition on, and don't start it. Yet on the forecourt, at Asda or anywhere else? Ask the attendants to help you push it clear of the pump. Next, 0333 366 0103. We will ask what got in, about how much, and if it has been run.
Say so if it was AdBlue rather than petrol: it's a different issue, with its own page for Coryton, because AdBlue brings corrosion and deposits rather than lost lubrication.
One petrol in a diesel task in Coryton costs more than another. Why?
The four situations above are four different jobs, so no single price for this would be honest. The situation itself does most of the work of moving the cost. Where the vehicle is matters too, and whether a van can safely get to it, after the proportion of petrol to what the tank takes.
Before any quote, not after, come three questions: your fuel that got in, the quantity, and whether it has run. That is why. Given the replies, you get a straight figure instead of a range.
About Coryton and its setting
Coryton is a suburban area in Cardiff, situated on the banks of the River Taff at an elevation of around 43 metres. Coryton lies approximately 3.8 miles northwest of Cardiff city centre, within close proximity to nearby places such as Pantmawr, Whitchurch, and Forest Farm. Coryton is characterised by its predominantly semi-detached housing stock, reflecting the typical residential architecture of the region. Coryton has a population of around 3659 residents, contributing to the wider Cardiff urban area.
Fuel drain cover across Cardiff, Coryton included
The vans answering petrol in diesel jobs around Coryton, in the CF postcode area, equally work the spots around it, Pantmawr, Whitchurch and Forest Farm among them. The vehicle does not need to move to us: our engineers drain at a forecourt, in a supermarket car park, in a lay-by or on your own driveway.
Still at the pump in Coryton?
Then, you couldn't be in a better spot. Keep it off. Ring.