How Worried Should You Be? Petrol in a Diesel Car in Upper Common
Not started? Then less anxious than you likely are. Everyone around Upper Common starts with "have I wrecked it?", and the fair answer is normally no: petrol left in the tank of any diesel remains harmless until priming, cranking or driving pulls it into the fuel system. Petrol in Diesel is who to phone, with the motor kept off, so it stays that way. What petrol really does to a diesel, how to judge how far it has gone, and how to stop it from happening again: that's the remainder of this page.
Petrol in a diesel: what does it do to your engine?
Passing through a motor, diesel does two things at once. It combusts, and before it ignites it protects. The high-pressure pump and the fuel injectors are designed to extremely fine gaps, and the diesel passing through them is what stops those surfaces from wearing down against each other.
Petrol handles the first task poorly and the second not at all. It is thinner than diesel and strips away the lubrication the fuel system depends 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 opposite of what a diesel needs from its fuel. That's where the rattling comes from.
Taken together, they make clear what shape the trouble takes. Contact doesn't do the damage — circulation does. Petrol in a tank is a fuel problem. Whatever a worn pump sheds goes on, borne by the fuel, into your injectors further along, which is why a pump that has worked on that petrol is where a mechanical problem starts.
Upper Common, petrol in a diesel: four cases, from mild to major
The best case there is: filled up, never started. The petrol is inside the tank and just your tank, and the task is a drain and a flush where your car stands. This is the one situation that can only really happen at a forecourt, because anywhere else the car has been driven to get there.
Ignition on, or started for a moment. Once primed, your system has pulled petrol from that tank as far as your filter and the fuel lines. Still usually straightforward: drain, flush, and the fuel filter seen to.
Driven a few miles. Now your pump has spent these miles working on thinned fuel. How hard the vehicle was driven matters as much as how far, and this work covers your tank, your lines, the fuel filter and clean fuel through the entire system. The school run to the local primary school is one matter. A run as far as Newport, under 25 miles away, is a very different task. So is any distance on the M4, under 25 miles from Upper Common, where your engine has been working hard throughout.
It protested, and only then stopped: smoke, rattling, a throttle gone soft, an idle gone ragged. That is your engine telling you its fuel has stopped behaving like diesel. Leave it where it stops: a lay-by, a quiet street, the verge on Common Road. What comes first is still the fuel drain and flush-through, and that deals with it, with lasting damage very uncommon when a vehicle is pulled over quickly.
What Upper Common people get told about petrol in a diesel — and the myths in it
It will not be fine. The myth: "Fill it the rest of the way with diesel and it will be." A fuller tank of the same mixture is all you get, since topping up removes nothing. Percentage isn't how a diesel fuel system copes with petrol, however much that advice assumes.
Myth: "A current diesel can cope with a bit of petrol." If anything, the reverse. A newer diesel runs its fuel through finer parts at higher pressure, which makes the protection matter more, not less.
This is the one that catches people. Myth: "If it starts and drives, there is no damage done." Diesel in a petrol motor normally means a motor that will not run: the driver stops, and so does the harm. Feed petrol to a diesel and it normally fires up, idles and pulls away like nothing has happened — all the while its pump is wearing. Fine and running aren't the same thing.
An old workaround for a different fault lies behind this one. Myth: "Add some two-stroke oil and drive it home." What petrol has weakened stays weakened, and that petrol remains in that tank regardless.
The next start sends petrol back round the pump from your lines and the fuel filter, where some of that ends up after your engine has run. That is why a DIY tank drain doesn't sort it — a myth. Draining petrol into a can at the kerbside is also really risky.
How does petrol in a diesel happen?
A careless moment is seldom the cause, and nobody means to do it. The petrol nozzle is the slimmer of the two and slides into a diesel filler with almost no resistance; a diesel nozzle mostly won't go into a petrol vehicle at all. The forecourt makes it easy, and the slip runs one way.
Habit and your car getting out of step is when it takes place. Hire cars, courtesy cars, and cars that are new to you. One petrol and one diesel on the drive of the same household. The pumps in a different order on a well-known forecourt. Fuelling up in a rush on the way to Abergavenny, with a train to catch. A new-to-you diesel Renault Megane, its first fuelling, and a motorist accustomed to petrol: exactly when it occurs. Your hand repeats what it has always done once you add rain, a phone call or a back seat full of children.
Preventing petrol in a diesel next time you fill up around Upper Common
- The label is what counts, so read the petrol pump rather than the colour: in the UK unleaded handles are usually green and diesel black, yet not on each forecourt.
- Check the filler flap. Many vehicles state the fuel inside the flap or on the cap. Look at it on your first fill in any vehicle you don't know.
- A coloured fob or a sticker on the diesel's key achieves more than any amount of meaning to remember, for a home with one of each.
- Say it before you lift it. On the first fill in a new or hired car, say "diesel" aloud before you lift the nozzle off the petrol pump. It seems daft and it does the trick.
- Thinking about something else is when this becomes an easy mistake to make, and so tuck your phone away and keep your mind on the pump.
- A misfuel inhibitor helps, up to a point. Some diesels have a filler designed to refuse a petrol nozzle, and add-on devices exist for motors without one. They are a safety net, not a reason to stop checking the petrol pump.
- Spotting it mid-fill? Stop at once. A thinner blend results from less petrol in your tank, but the next stage remains the same: don't fire it up.
Put petrol in a diesel around Upper Common already?
The order of things is brief, then. Don't switch your ignition on, and do not crank it. If you are still on the forecourt — Gulf or anywhere else — ask the staff to help you push the car clear of the pump. Next, 0333 366 0103. We will ask what went in, about how much, and if it has been run.
Say so if it was AdBlue instead of petrol: it is a different issue, with its own page for Upper Common, since AdBlue brings corrosion and deposits rather than lost lubrication.
Upper Common petrol in a diesel tasks: why one costs more than another
There is no fair single price for this, because the four scenarios above are four different jobs. Which of them you're in is chiefly what moves your cost. The proportion counts next, meaning how much of your tank is petrol, followed by the position of your car and whether getting to it is safe for a van.
Ahead of any quote, not after, come three questions: your fuel that went in, the volume, and whether it has run. That's why. Given the answers, there is a straight figure rather than a range.
About Upper Common itself
Upper Common is a suburban area located on the riverside in Monmouthshire, Wales, with a mix of detached housing and a population of around 2235 residents. Upper Common sits at an elevation of 82 metres, near the communities of Lower Common and Gilwern, and is approximately 17 miles from Newport. Upper Common is part of a wider area that includes nearby Pen-y-bont and other small settlements along the river. Upper Common has a relatively low elevation compared to other areas in the region, which are often hillier and more rural.
Across Monmouthshire and in Upper Common: fuel drain cover
The teams answering petrol in diesel jobs in Upper Common, in the NP postcode area, also work the places near it, Lower Common, Gilwern and Pen-y-bont among them. You need not move the car to us. Forecourts, supermarket car parks, lay-bys and your own driveway are all places we drain.
Upper Common: still at the pump?
No position is better: that's where you are. Switched off it remains; then phone.