Oxlease: Petrol in a Diesel Car? How Worried to Be
Far less than you likely are, provided it hasn't been started. Petrol resting in a diesel tank does nothing to your motor until something pulls it through the fuel system — the ignition priming the pump, the starter, or the drive on its own. So the truthful answer to the first question anyone in Oxlease asks, "have I ruined it?", is usually no. Petrol in Diesel is who to ring, with your engine left off, so it stays that way. The rest of this page explains what petrol really does to a diesel, how to tell how far it has got, and how to make sure it doesn't happen to you a second time.
What petrol in a diesel does to the motor
Diesel does two tasks on its way through a motor. It burns, and before it combusts it protects. Designed to very fine tolerances, the injectors and the pump rely on the diesel moving through them to keep their surfaces from wearing against one another.
The second task petrol doesn't do at all, and the first it does poorly. A pump working on a petrol mix is wearing itself out, since petrol is runnier than diesel and takes away the lubrication your fuel system depends on. Petrol is also designed to resist igniting under compression — the opposite of what a diesel needs from its fuel — and that's where the rattling comes.
Seen together, they show what shape the trouble takes. Not contact but circulation is what does the harm. Where the petrol is only inside the tank, it is an issue of fuel, nothing more. A pump that has been labouring on that petrol is the start of a mechanical one, and whatever a worn pump sheds moves on with your fuel to your injectors downstream.
How bad is petrol in a diesel? Four scenarios our technicians see in Oxlease
Fuelled up, not once started. The best case there can be. Being at a forecourt is what makes this possible: elsewhere, the car has been driven there to begin with. With that petrol held inside the tank alone, it's drained and flushed right where it stands, and nothing more is needed.
Ignition on, or started for a second. Petrol has come out of the tank and reached the filter and your lines, because the fuel system has been bled. That's normally still a straightforward task — a drain, a flush, and the filter dealt with.
A few miles driven, and the pump has spent every one of them working on diluted fuel. How hard your car was driven counts as much as how far, and the work covers that tank, the fuel lines, the filter and fresh fuel through the entire circuit. On the school run to Oak View Primary and Nursery School, the mileage is short. Any mileage on the A1(M), under a mile from Oxlease, means the engine has worked hard throughout, and a run to St Albans, under 5 miles away, makes a very different task too.
Driven till it protested. Knocking, an uneven idle, smoke, a throttle that has gone soft. That is the motor telling you its fuel has stopped behaving like diesel. Leave it where it stops: a lay-by, a quiet street, the verge on Travellers Lane. A car pulled over quickly very seldom has lasting damage, because the drain and the flush, which still come first, take care of it.
Myths Oxlease drivers hear about petrol in a diesel
Myth: "Fill it the rest of the way with diesel and it will be fine." It will not. Nothing is removed by topping up — you are left with a bigger tank, still the same mixture. Percentage is not how a diesel fuel system tolerates petrol, whatever that guidance assumes.
"Newer diesels can handle a little petrol" — a myth, and closer to the reverse. More precise 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 there is no harm" — the myth that catches most motorists than any other. The motorist of a petrol engine fed diesel normally has no choice but to stop, because it will not run, and the harm stops there. Feed petrol to a diesel and it normally starts, ticks over and drives away like nothing has happened — all the while its pump wears. Running is not the same as fine.
An old workaround for a different problem is behind this one. Myth: "Add some two-stroke oil and drive the vehicle home." What petrol has weakened stays thinned, and the petrol stays in the tank anyway.
"Drain it yourself and you're sorted" — a myth, because after it has been running some petrol sits in the filter and lines, ready to go straight back through your pump at the next start. Also, a can of petrol filled at the kerbside is truly hazardous.
How it happens: petrol in a diesel
Nobody does it on purpose, and it is seldom carelessness. One way only, because of the nozzles: the narrower petrol one slides inside a diesel filler with almost no resistance, while the diesel one generally won't fit a petrol car. That is how the forecourt makes it straightforward.
When routine and your car stop matching, it occurs. Any vehicle that's new to you — hired, on loan as a courtesy car, or just bought. A household with one petrol and one diesel on the drive. A well-known forecourt with the pumps in a different order. A train to catch, and a rushed fill en route to Hatfield. The first fill-up in a diesel Renault Clio after years of driving petrol is precisely the moment it takes place. With rain, a call arriving, or a car full of children to deal with, the hand just does what it has always done.
How to prevent petrol in a diesel on your next fill-up in Oxlease
- Read the pump, not the colour. In the UK unleaded handles are generally green and diesel black, but not on each forecourt. The label is what counts.
- The first fill in an unfamiliar motor is the time to check your filler flap — on it, or on the cap, many cars state the fuel they take.
- One of each in the household? Label the key to the diesel — a coloured fob, a sticker — because intending to remember isn't enough.
- Say it before you lift it. On your first fill in a new or hired car, say "diesel" aloud before you take the nozzle off the petrol pump. It sounds silly and it works.
- Tuck the phone away. This is an easy mistake to make while you are thinking about something else.
- Add-on devices are available for vehicles without one, and some diesels come with a filler that will not accept a petrol nozzle. Helpful — but a safety net only, never a reason to stop checking the label.
- As soon as you realise, stop: less petrol inside your tank means a thinner blend. What to do next does not change, though — still don't start it.
Oxlease: already put petrol in a diesel?
Then the order of things is brief. Leave it unstarted, with your ignition switched off as well. Yet on the forecourt, at Gulf or anywhere else? Ask the attendants to help you push the vehicle away from the petrol pump. Then call 0333 366 0103 and tell us what got in, roughly how much, and whether it's run.
Say so if it was AdBlue rather than petrol: it's a different issue, with its own page for Oxlease, since AdBlue brings corrosion and deposits instead of lost protection.
Oxlease petrol in a diesel jobs: why one costs more than another
There is no honest single quote for this, since the four scenarios above are four separate tasks. The scenario itself does most of the work of moving your cost. The ratio matters next, meaning how much of that tank is petrol, and then the position of your car and whether getting to it is safe for our van.
What got in, how much, and whether it's run — three questions we ask before costing, not after, for precisely that reason. Those replies change a range into a straight figure.
About Oxlease and where it is
Oxlease is a suburban area in Hertfordshire, situated approximately 4.8 miles from St Albans and 17.6 miles from London. Oxlease sits at an elevation of around 86 metres, in a gently sloping landscape near the towns of South Hatfield and Hatfield. Oxlease is characterized by its predominantly terraced housing stock, which reflects the area's development as a residential community. Oxlease is bordered by nearby places such as Roe Green, which share similar geographical and demographic profiles.
Oxlease and Hertfordshire: where our fuel drain cover reaches
South Hatfield, Roe Green and Hatfield are among the locations near Oxlease that the same vans work, answering petrol in diesel jobs across Oxlease's AL postcode area. You need not bring the vehicle to us. Forecourts, supermarket car parks, lay-bys and your own driveway are all locations we drain.
In Oxlease and still at the petrol pump?
In that case, you couldn't be in a better place. Leave the vehicle turned off, then ring.