Roxburghs Court: Petrol in a Diesel Car? How Worried to Be
Not started? Then less worried than you likely feel. Until your ignition primes your pump, your starter turns, or your car is driven, petrol in a diesel tank simply waits there and does nothing. Which makes the truthful reply to the first Roxburghs Court query — "have I wrecked it?" — usually no. Keep it that way: leave the motor off and ring Petrol in Diesel. Below, you will find what petrol actually does inside a diesel, how far it may have gone, and how to stop it happening to you a second time.
What petrol in a diesel does to the engine
Two jobs fall to diesel on its journey round a motor. Before it ignites, it lubricates — and then it ignites. Very fine gaps are built into your injectors and the high-pressure fuel pump, and just the diesel flowing through keeps those surfaces from grinding together.
Of those two tasks, petrol handles the first badly and the second not at all. A pump running on a petrol mixture is wearing itself out, since petrol is runnier than diesel and strips out the lubrication the fuel system relies on. Petrol is also designed to resist igniting under compression — the opposite of what a diesel wants from its fuel — and that's where the clattering starts.
Taken together, they show the shape the trouble takes. The harm is done by circulation, not by contact. Petrol in a tank is a fuel fault. Once the pump has been running on that petrol, a mechanical problem has begun: anything shed by a pump that's grinding is carried onward to the fuel injectors with the fuel.
Four scenarios our technicians see around Roxburghs Court: how serious is petrol in a diesel?
Fuelled up, not once started. The best case there is. On a forecourt, and truly only there, that petrol is still confined to the tank — because anywhere else the car was driven to reach it. The job is draining and purging on the spot.
A moment's running, or merely the ignition on. With the system primed, the fuel lines and filter already contain petrol that came from that tank. Drain, flush, deal with the fuel filter: still normally easy.
Some miles driven, and the pump has spent each of them labouring on weakened fuel. Mileage is only half of that; how hard it was driven matters just as much. Either way this work includes the tank, the lines, your filter and clean fuel through the whole circuit. On the school run to the local primary school, the miles is short. Very different a second time: a run to Edinburgh, under a mile away, or any distance on the M8, under 5 miles from Roxburghs Court, where the engine kept running hard.
Clattering, a ragged idle, smoke, a throttle gone soft: driven until it complained. The fuel isn't acting like diesel any more, and your engine is telling you. Leave it where it has stopped: a lay-by, a quiet street, the verge on High Street. A car pulled over early very rarely has long-term damage, since the fuel drain and the flush, which still go first, sort it out.
Petrol in a diesel stories Roxburghs Court drivers hear
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 mix is all it gives, because topping up takes out nothing. Percentage is not how a diesel fuel system tolerates petrol, whatever that guidance presumes.
Myth: "A newer diesel can cope with a bit of petrol." If anything, the reverse. A newer diesel sends its fuel through finer parts at higher pressure, which makes the protection count more, not less.
Myth: "If it starts and drives, there is no damage done." This is the one that fools people. A petrol motor fed diesel normally will not run, so the motorist stops and the damage stops with them. Nothing seems to have happened when a diesel fed petrol fires up, ticks over and drives away, as it usually will; meanwhile your pump wears. Being able to run isn't proof of being fine.
"A drop of two-stroke oil and drive it home" — a myth, taken from a fix from years ago, for a different issue. What petrol has weakened stays diluted, and that petrol remains inside that tank regardless.
The next start sends petrol back round the pump from the lines and the filter, where some of it sits once the engine has run. That's why draining your tank yourself doesn't sort it — a myth. And, a can of petrol filled at the roadside is genuinely risky.
How does petrol in a diesel occur?
It's seldom carelessness, and no one does it on purpose. A diesel nozzle mostly won't fit a petrol car, yet the smaller petrol nozzle goes into the filler of a diesel nearly without resistance — so forecourts make this one error straightforward, and only in that direction.
It occurs when routine and the car stop matching. Hire cars, courtesy cars, and vehicles that are new to you. Households running one of each, petrol and diesel. The pumps in a different order on a familiar forecourt. A hurried fill en route to Edinburgh Waverley with a train to catch. A new-to-you diesel Volkswagen Golf, its first fuelling, and a driver used to petrol: exactly when it happens. The hand repeats what it has always done when you add rain, a phone call or a back seat full of children.
Roxburghs Court motorists: how to avoid petrol in a diesel next time
- Check the petrol pump, not the colour. In the UK unleaded handles are normally green and diesel black, yet not on each forecourt. The label is what counts.
- Check the filler flap. Many vehicles state the fuel inside the flap or on the cap. Look at it on your first fill in a vehicle you do not know.
- A coloured fob or a sticker on your diesel's key does more than any amount of intending to remember, in a home with one of each.
- Say it before you lift it. On your first fill in a new or hired car, say "diesel" out loud before you lift the nozzle off the pump. It seems silly and it works.
- Tuck the phone away. This is an easy mistake to make whilst you're thinking about something else.
- 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 backstop, not a reason to stop checking the pump.
- Less petrol makes a thinner blend, and so stop as soon as you realise — while remembering that your next stage is unchanged. It's still not to fire it up.
Already put petrol in a diesel around Roxburghs Court?
Then, there is only a short order of things. Do not switch your ignition on, and do not fire it up. Still at the forecourt, at JET or anywhere else? Ask the attendants to help you push it clear of the petrol pump. Then phone 0333 366 0103 and tell us what got in, about how much, and whether it has run.
AdBlue, not petrol? Then tell us. Corrosion and deposits, not lost lubrication, make it a separate fault — Roxburghs Court has a page just for it.
What makes one Roxburghs Court petrol in a diesel job cost more than the next
Four separate tasks lie behind the four scenarios above — which is why there's no fair single price. Mostly, the cost moves with which situation you're in. The ratio counts next, meaning how much of your tank is petrol, followed by the position of the vehicle and whether getting to it is safe for a technician.
That's why our engineers ask three queries before costing instead of after: what got in, how much, and if it has run. Their answers are what change a range into one firm number.
About Roxburghs Court
Roxburghs Court is a locality in the City of Edinburgh, situated near the coast and close to the historic Old Town. Roxburghs Court sits at an elevation of 93 metres, overlooking the surrounding area. Roxburghs Court is predominantly composed of flat-type housing, reflecting the urban character of the area. Roxburghs Court is located in close proximity to Edinburgh, being only 0.2 miles away from the city centre.
Fuel drain cover around Roxburghs Court and across City of Edinburgh
The vans answering petrol in diesel calls around Roxburghs Court, in the EH postcode area, also work the spots around it, Old Town, Edinburgh and South Side included. You need not bring the car to us. Forecourts, supermarket car parks, lay-bys and your own driveway are all places we drain.
Still at the pump around Roxburghs Court?
Then you're in the best spot there is. Keep it off. Call.