How Worried Should You Be? Petrol in a Diesel Car in Forebridge
Far less than you likely are, provided it hasn't been started. Until your ignition primes your pump, your starter turns, or your car is driven, petrol in a diesel tank simply waits there and does no harm. Which means the honest reply to that first Forebridge query — "have I wrecked it?" — normally no. To keep the car that way, phone Petrol in Diesel then leave the engine alone. The rest of this page covers what petrol really does to a diesel, how to judge how far it has got, and how to make sure it does not happen to you again.
Inside the motor: what petrol in a diesel does
On its way through an engine, diesel does two jobs. It protects first, and after that does it burn. Very fine gaps are built into your injectors and your high-pressure pump, and just the diesel flowing through keeps those surfaces from grinding together.
Of those two jobs, petrol handles the first badly and the second not at all. It's runnier than diesel and strips away the lubrication the system depends on, and so a pump running on a petrol mix is a pump wearing itself. And petrol is made to resist igniting under compression, which is the reverse of what a diesel needs from its fuel. That is where the knocking comes from.
The shape of the trouble is plain once you put those together. Not contact but circulation is what causes the damage. A tank with petrol in it is a fuel problem. Once the pump has been running on that petrol, a mechanical issue has started: anything shed by a pump that's wearing down travels downstream to the injectors with the fuel.
How bad is petrol in a diesel? Four situations we see around Forebridge
Fuelled up, never started. The best case there is. That petrol is in the tank and only your tank, and the job is a drain and a flush where the car sits. This is the one scenario that can only really take place at a forecourt, as anywhere else your car has been driven to get there.
The ignition turned on, or a short start. The fuel system has been primed, so petrol has left that tank and got to your filter and your lines. Drain, flush, deal with the fuel filter: still usually easy.
A couple of miles driven, and your pump has spent every one of them running on weakened fuel. Tank, lines, filter, then fresh fuel run through the entire system: that is the work, and the way the vehicle was driven counts as much as the miles. Short trips, like the school run to St Paul's Church of England Primary School, are one thing. Very different a second time: a run to Lichfield, under 15 miles away, or any mileage on the M6, under 3 miles from Forebridge, where the motor never stopped working hard.
Driven until it complained. Rattling, a lumpy idle, smoke, a throttle that has gone soft. The engine is telling you the fuel is no longer behaving like diesel. Leave it wherever it stops: a lay-by, a side street, the verge on New Garden Street. Long-term damage is very rare when a car is stopped quickly, and the drain and flush-through that still come first take care of it.
Forebridge drivers and that 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." Topping up takes out nothing; it gives you a fuller tank of the same mix. The assumption behind the advice — that diesel fuel systems tolerate petrol by percentage — is wrong.
Myth: "A current diesel can cope with a bit of petrol." If anything, the opposite. Smaller parts and higher pressure are the way a current diesel runs its fuel, and that makes the lubrication count more, not less.
"It starts, it drives, and so no harm done" — the myth that catches most motorists than any other. Feed diesel to a petrol motor and it normally won't run, and so the driver stops — and the harm stops with them. A diesel fed petrol usually starts, idles and drives away as though nothing has happened, while your pump grinds. Fine and running aren't the same thing.
Not so: a two-stroke additive makes it safe to drive home. It is an old fix, supposed for another fault. What petrol has diluted remains thinned, and the petrol stays inside that tank regardless.
The next start draws petrol back round the pump from your lines and your filter, where some of it ends up once your engine has run. That's why draining the tank yourself doesn't leave you sorted — a myth. It's also genuinely dangerous to drain petrol into a can by the roadside.
Why petrol in a diesel occurs so easily
On purpose? Never. Through carelessness? Rarely, if ever. One way only, because of the nozzles: the narrower petrol one slides inside a diesel filler with almost no resistance, whereas the diesel one mostly won't fit a petrol car. That is how the forecourt makes it simple.
The moment routine stops matching the vehicle is the moment it occurs. Courtesy car, hire car, or a vehicle that is brand new. One petrol and one diesel on the driveway of the same household. Your ordinary forecourt, its pumps now in a different order. Fuelling up in a rush on the way to Stafford, with a train to catch. The first fill-up in a diesel Renault Megane after years of driving petrol is precisely the moment it happens. Throw in rain, a phone call or a back seat full of children, and the hand repeats what it has always done.
Forebridge drivers: how to avoid petrol in a diesel next time
- The label is what counts, so check the petrol pump instead of the colour: in the UK unleaded handles are normally green and diesel black, but not on every forecourt.
- Plenty of cars state the fuel type inside the filler flap or on the cap, so check it on your first fill in any motor you don't know.
- A coloured fob or a sticker on the diesel's key does more than any amount of meaning to remember, for a house with one of each.
- Before the nozzle comes off the pump the first time you fill a hired or new car, say "diesel" aloud. Daft, yes, but it works.
- 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 pump.
- Add-on devices exist for motors without one, and some diesels come with a filler that will not take a petrol nozzle. Helpful — but a safety net at best, never a reason to stop checking the label.
- Less petrol makes a thinner blend, so stop the moment you notice — though remembering that your next stage is unchanged. It is still not to crank it.
Petrol already in a diesel in Forebridge? Start here
Then, there is just a short order of things. Do not start the vehicle, and do not switch your ignition on. Ask the staff to help you push it clear of the petrol pump if you are still on the forecourt, whether that is Asda or anywhere else. Next, 0333 366 0103. We'll ask what went in, roughly how much, and if it has been run.
Corrosion and deposits are the trouble with AdBlue, where petrol brings lost lubrication. So if it was AdBlue, say so — and read its own Forebridge page.
Forebridge petrol in a diesel jobs: why one costs more than another
Four different jobs sit behind the four scenarios above — which is why there is no honest single quote. What shifts the cost is chiefly which of them you're in. Where the vehicle is matters too, and whether a van can safely get to it, after the share of petrol to what your tank takes.
What was put in, how much, and if it's run — three queries we ask before pricing, not after, for exactly that reason. The replies turn a range into a straight figure.
About Forebridge, briefly
Forebridge is a suburban area in Staffordshire, situated on the riverside with an elevation of 82 metres. Forebridge lies near the city of Lichfield and the towns of Stafford and Broadeye, and is characterized by its predominantly terraced housing. Forebridge is part of a larger urban landscape, with nearby places including Rowley Park, and is approximately 122.7 miles from London.
Across Staffordshire and in Forebridge: fuel drain cover
Forebridge sits in the ST postcode area, and the teams that answer petrol in diesel calls there work the locations near it as well — Stafford, Broadeye and Rowley Park among them. Our engineers drain wherever the vehicle is — your own driveway, a lay-by, a supermarket car park, a forecourt — so it never needs to come to us.
Still at the pump in Forebridge?
The best place there is, then — that is where you are. Phone, and keep it switched off.