Newtown: Petrol in a Diesel Car? How Worried to Be
If it has not been started, worry far less than you probably are. Petrol resting in a diesel tank does nothing to your motor till something draws it through the fuel system — the ignition priming the pump, the starter, or the drive itself. So the truthful answer to the first question anyone in Newtown asks, "have I ruined it?", is normally no. Leave the motor off and call Petrol in Diesel — that is how you keep it like that. What petrol really does to a diesel, how to judge how far it has gone, and how to stop it from happening a second time: that's the rest of this page.
Inside the motor: what petrol in a diesel really does
On its way through a motor, diesel does two tasks. It lubricates first, and after that does it burn. Extremely fine gaps are built into the fuel injectors and the high-pressure fuel pump, and only your diesel running through stops their surfaces grinding together.
Badly at the first, not at all at the second: that's petrol. A pump running on a petrol mixture is wearing itself out, because petrol is thinner than diesel and takes away the lubrication the fuel system depends on. Petrol is also made to resist igniting under compression — the opposite of what a diesel needs from its fuel — and that's where any knocking starts.
The shape of the issue is clear once you put those together. Contact does not do the damage — circulation does. All a tank with petrol in it amounts to is a fuel problem. A pump that has been running on that petrol is the start of a mechanical one, and whatever a worn pump sheds travels on with the fuel to the fuel injectors further on.
Four scenarios our engineers see around Newtown: how bad is petrol in a diesel?
Filled but not once started — as good as it gets. On a forecourt, and truly only there, the petrol is still limited to that tank — since anywhere else the car was driven to get to it. The job is draining and rinsing on the spot.
Started for a moment, or only the ignition on. Petrol has come out of your tank and got to the fuel filter and the fuel lines, because the fuel system has been primed. Still usually simple: drain, flush, and your filter dealt with.
Those few miles on the road meant your pump working on fuel weakened by petrol the whole way. The work is that tank, the fuel lines, your filter and fresh fuel through the entire circuit, and how hard your car was driven counts as much as how far. Short trips, like the school run to Trinity Church of England Primary School, are one matter. Very different again: a run to Oxford, under 25 miles away, or some distance on the A404(M), under 10 miles from Newtown, where the engine never stopped labouring hard.
It protested, and only then stopped: smoke, rattling, a throttle gone soft, an idle gone lumpy. What you are hearing is your engine signalling fuel that no longer acts like diesel. Leave it wherever it has stopped: a lay-by, a side street, the verge on Western Avenue. A car stopped soon very rarely has lasting damage, since the drain and the flush, which still come first, sort it out.
Newtown drivers and that petrol in a diesel myths they hear
"Top it up the rest of the way with diesel and it'll be fine" — a myth. It won't. A fuller tank of the same mixture is all it gives, since topping up takes out nothing. The idea behind that guidance — that diesel fuel systems tolerate petrol by percentage — is wrong.
If anything, the opposite holds. Myth: "A current diesel can cope with a bit of petrol." At higher pressure, through more precise parts: that is how a current diesel handles its fuel, and so the protection counts for more, not less.
Myth: "If it starts and drives, there's no damage done." This is the one that fools drivers. The driver of a petrol motor fed diesel usually has no choice but to stop, because it will not run, and the damage stops with them. Feed petrol to a diesel and it normally starts, ticks over and pulls away as if nothing happened — all the while its pump is wearing. Fine and running are not the same at all.
Myth: "Add some two-stroke oil and drive it home." It is an old workaround for a distinct issue. What petrol has weakened remains thinned, and the petrol stays inside the tank anyway.
"Drain it yourself and you're sorted" — a myth, since after it's been running some petrol sits in your filter and lines, ready to go straight back through the pump at your next start. Draining petrol into a can at the roadside is also truly risky.
How it happens: petrol in a diesel
It's seldom carelessness, and nobody does it on purpose. One way only, because of the nozzles: the slimmer petrol one slips inside a diesel filler with almost no resistance, whereas the diesel one generally won't fit a petrol vehicle. That's how the forecourt makes it straightforward.
The moment routine stops matching your car is the moment it takes place. A new motor, a hire car or a courtesy car. Households running one of each, petrol and diesel. A forecourt you know, only with its pumps arranged differently. Fuelling up in a rush on the way to Henley-On-Thames, with a train to catch. A new-to-you diesel Volkswagen Passat, its first fuelling, and a motorist used to petrol: exactly when it occurs. Throw in a back seat full of kids, a phone call or rain, and the hand wins.
Next time you fill up in Newtown: avoiding petrol in a diesel
- Check the pump, not the colour. In the UK unleaded handles are normally green and diesel black, but not on every forecourt. The label is what matters.
- The first fill in a strange vehicle is the time to check the filler flap — inside it, or on the cap, plenty of motors state the fuel they take.
- A coloured fob or a sticker on your diesel's key does more than any amount of meaning to remember, for a household 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 silly and it does the trick.
- Whilst you are thinking about something else, this is an easy mistake to make — so put the phone away.
- Add-on devices are available for vehicles without one, and some diesels come with a filler that won't take a petrol nozzle. Helpful — but a safety net only, never a reason to stop checking the label.
- Noticing it halfway? Stop there and then. A weaker blend results from less petrol in that tank, yet your next step stays the same: don't start the car.
Petrol already in a diesel around Newtown? Start here
Short and simple, then, is the order of things. Starting it is out, and so is switching on your ignition. Still at the forecourt, at Shell or anywhere else? Ask the staff to help you push the car away from the petrol pump. Next, 0333 366 0103. We will ask what went in, about how much, and if it's been run.
Corrosion and deposits are the trouble with AdBlue, whereas petrol means lost protection. So if it was AdBlue, say so — and read its own Newtown page.
What makes one Newtown petrol in a diesel task cost more than the next
A fair single quote does not exist here: four scenarios, four separate tasks. The situation itself does most of the work of moving the cost. Two things come after that: the petrol that was put in as a share of what the tank takes, then the spot the car is in and whether a technician can reach it safely.
That's why we ask three questions before quoting rather than after: what got in, how much, and if it's run. The replies change a range into a straight figure.
About Newtown, for a moment
Newtown is a suburban area in Oxfordshire, situated on the riverside at an elevation of 41 metres. Newtown lies near the town of Henley-on-Thames and the villages of Harpsden and Harpsden Heights, within commuting distance of Oxford. Newtown has a population of approximately 5305 people, predominantly living in terraced housing. Newtown is located 33.3 miles from London, making it a potential base for those working in the capital.
Newtown and Oxfordshire: where our fuel drain cover runs
Newtown waits in the RG postcode area, and our teams that answer petrol in diesel jobs there work the places near it as well — Harpsden Heights, Harpsden and Henley-on-Thames among them. The car doesn't need to move to us: we drain on a forecourt, in a supermarket car park, in a lay-by or on your own drive.
In Newtown and still at the pump?
Then you're in the best place there can be. Keep it off. Call.