Petrol in a Diesel Car in High Cross: How Worried Should You Be?
If it has not been started, you can worry far less than you probably are. Till the ignition primes your pump, your starter turns, or the vehicle is driven, petrol in a diesel tank just sits there and does nothing. Which means the honest reply to the first High Cross question — "have I ruined it?" — usually no. Petrol in Diesel is who to phone, with the engine kept off, and so it stays that way. What petrol actually does to a diesel, how to gauge how far it has gone, and how to keep it from happening again: that's the remainder of this page.
Inside the engine: what petrol in a diesel does
Two jobs fall to diesel on its route round a motor. It burns, and before it ignites it protects. What keeps the surfaces inside the high-pressure fuel pump and the injectors from wearing down against one another is the diesel flowing through them — they are made to very fine tolerances.
Petrol does the first job badly and the second not at all. It is runnier than diesel and removes the lubrication your fuel system depends on, and so a pump running on a petrol mixture 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.
Together, those make the shape of the issue clear. It's circulation that causes the harm, not contact. Any tank with petrol in it is a fuel problem. The beginning of a mechanical problem is a pump that has been running on that petrol — and whatever a worn pump sheds travels on with the fuel to the fuel injectors beyond it.
High Cross, petrol in a diesel: four cases, from mild to serious
Filled up, not once started. The best case there can be. Just that tank has petrol in it, and so the job is draining the tank and rinsing the system where your car stands. This situation can only really happen at a forecourt: anywhere else, the car got there by being driven.
Ignition on, or started for a moment. The fuel system has been bled, so petrol has left your tank and reached your filter and the fuel lines. Drain, flush, deal with the fuel filter: still usually straightforward.
A couple of miles driven, and your pump has spent each of them working on weakened fuel. Mileage is only half of it; how hard it was driven counts equally. Either way this work includes the tank, the fuel lines, your filter and clean fuel through the entire system. On the school run to the local primary school, the mileage is short. Very different a second time: a trip to Newport, under 3 miles away, or some miles on the M4, under a mile from High Cross, where the motor kept labouring hard.
Knocking, a ragged idle, smoke, a throttle gone soft: driven till it complained. What you are hearing is the motor reporting fuel that no longer runs like diesel. Leave it wherever it has stopped: a lay-by, a quiet street, the verge on Myrtle Drive. The drain and flush still come first, and they deal with it: when a vehicle is stopped early, long-term damage is very unusual.
Myths High Cross drivers hear about petrol in a diesel
Myth: topping up to full with diesel makes it fine. It does not. Nothing comes out when you top up — the tank simply holds more of the same mixture. Percentage isn't how a diesel fuel system tolerates petrol, however much that guidance assumes.
Myth: "A modern diesel can cope with a bit of petrol." If anything, the reverse. A current diesel sends its fuel through smaller parts at higher pressure, which makes the lubrication matter more, not less.
One myth that catches people out: if it starts and drives, it must be unharmed. Feed diesel to a petrol motor and it usually will not run, and so the driver stops — and the harm stops with them. Nothing looks to have happened when a diesel fed petrol fires up, ticks over and drives away, as it usually will; meanwhile your pump grinds. Running is not the same as fine.
An old fix for a different issue is behind this one. Myth: "Add some two-stroke oil and drive it home." The petrol is still inside your tank after that, and whatever it has weakened is not put back.
Myth: "Drain that tank yourself and you are sorted." After the motor has been run, some of the petrol is no longer inside your tank: it's in the fuel filter and the lines, and it goes straight back through your pump on your next start. It is also genuinely hazardous to drain petrol into a can by the roadside.
Petrol in a diesel: how does it take place?
Carelessness is rarely the cause, and nobody means to do it. The forecourt makes it simple: the petrol nozzle is the smaller of the two, and it slips into a diesel filler with almost no resistance, whilst a diesel nozzle mostly won't go into a petrol motor at all. So the mistake runs one way.
The moment habit stops matching the vehicle is the moment it takes place. Courtesy car, hire car, or a car that is new. Households running one of each, petrol and diesel. Your ordinary forecourt, its pumps now in a different order. Filling up in a hurry en route to Pye Corner, with a train to catch. Exactly the moment it takes place: after years of driving petrol, someone fills a diesel Renault Megane for the first time. Your hand repeats what it has always done when you add rain, a phone call or a back seat full of kids.
How to avoid petrol in a diesel at your next fill-up in High Cross
- Check the pump, not the colour. In the UK unleaded handles are normally green and diesel black, yet not on each forecourt. The label is what matters.
- In a car you do not know, look inside the flap over the filler or at the cap before your first fill: plenty of motors print the fuel type there.
- A coloured fob or a sticker on the diesel's key achieves more than any amount of meaning to remember, in a household with one of each.
- It sounds silly and it works: on the first fill in a new or hired car, say "diesel" aloud before you take the nozzle off the petrol pump.
- Put your phone away. This is an easy mistake to make while you're thinking about something else.
- Some diesels have a filler built to refuse a petrol nozzle, and devices you can add exist for motors without one. Such an inhibitor helps up to a point — as a safety net, not a reason to stop checking the petrol pump.
- Spotting it mid-fill? Stop at once. A weaker blend follows from less petrol inside your tank, but the next stage remains the same: don't start it.
Petrol already in a diesel in High Cross? Begin here
Then, there's only a short order of things. Leave it unstarted, with your ignition off as well. If you're still at the forecourt — Asda or anywhere else — ask the attendants to help you push the car away from the petrol pump. What was put in, about how much, and if it has run: tell us those when you phone 0333 366 0103.
Say so if it was AdBlue rather than petrol: it is a different fault, with its own page for High Cross, because AdBlue brings corrosion and deposits rather than lost lubrication.
High Cross petrol in a diesel jobs: why one costs more than another
There's no fair single price for this, because the four scenarios above are four separate tasks. What moves the cost is mostly which of them you're in. Where your car is matters too, and whether a van can safely get to it, after the ratio of petrol to what that tank takes.
That's why our engineers ask three queries before costing rather than after: what got in, how much, and whether it has run. A range turns into a straight figure once those replies are in.
About High Cross
High Cross is a suburban area located on the riverside in Newport, Wales, with a relatively low elevation of 31 metres. High Cross sits close to the city centre, approximately 2.1 miles from Newport, and is near other local places such as Bassaleg and Glasllwch. High Cross has a population of around 4562 people and predominantly consists of semi-detached housing.
Fuel drain cover around High Cross and across Newport
Petrol in diesel calls around High Cross — part of the NP postcode area — go to vans that also cover the locations around it, Bassaleg, Glasllwch and Rhiwderin among them. The car does not need to come to us: we drain at a forecourt, in a supermarket car park, in a lay-by or on your own driveway.
At the pump around High Cross, still?
No position is better: that's where you are. Keep it off. Call.