Should You Worry? Petrol in a Diesel Car in Hillingdon
Unstarted? Then less anxious than you likely feel. Until the ignition primes the pump, your starter turns, or your vehicle is driven, petrol in a diesel tank just sits there and does nothing. Which makes the honest reply to that first Hillingdon query — "have I wrecked it?" — normally no. To leave the vehicle like that, ring Petrol in Diesel then leave your motor alone. What petrol really does to a diesel, how to judge how far it has travelled, and how to stop it from happening again: that's the remainder of this page.
The motor and petrol in a diesel: what happens
Two tasks fall to diesel on its route through a motor. Before it burns, it protects — then it combusts. Made to very fine gaps, the fuel injectors and the pump rely on your diesel flowing through them to keep their surfaces from wearing against one another.
Petrol handles the first task poorly and the second not at all. The rattling comes from petrol being made not to ignite when compressed, which is exactly the opposite of what a diesel needs. On top of that it is thinner than diesel, it strips out the lubrication the system hinges on, and any pump running on such a blend is wearing itself.
Taken together, they show what shape the issue takes. Contact doesn't do the damage — circulation does. A tank with petrol in it is a fuel problem. 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 the fuel to your injectors further on.
How serious is petrol in a diesel? Four scenarios we see in Hillingdon
Filled but not once started — as good as it gets. Being at a forecourt is what makes this the case: elsewhere, your car has been driven there to begin with. With that petrol kept in the tank alone, it is drained and rinsed right where it stands, and nothing more is needed.
Ignition on, or started for a second. Once primed, the fuel system has drawn petrol out of that tank as far as the filter and the fuel lines. Usually little more than emptying, purging and sorting the fuel filter, so still easy.
Driven a few miles. Now your pump has spent these miles working on diluted fuel. The work is your tank, the fuel lines, the fuel filter and fresh fuel through the entire circuit, and how hard the car was driven matters as much as how far. Driving the children to Oak Farm Primary School is one kind of trip. Very different again: a run to Westminster, under 15 miles away, or any mileage on the M40, under 3 miles from Hillingdon, where the engine never stopped labouring hard.
Driven until it protested. Knocking, a lumpy idle, smoke, a throttle that has gone soft. That is your motor telling you its fuel has stopped acting like diesel. Leave it where it stops: a lay-by, a quiet street, the verge on Long Lane. What goes first is still the fuel drain and flush, and that deals with it, with lasting damage very rare if a vehicle is stopped quickly.
Stories Hillingdon drivers hear about petrol in a diesel
Myth: "Fill it the rest of the way with diesel and it'll be fine." It will not. Nothing is removed by topping up — you're left with a bigger tank, still the same mixture. Percentage is not how a diesel fuel system tolerates petrol, however much that advice presumes.
"Current diesels can handle a little petrol" — a myth, and closer to the reverse. At higher pressure, through smaller components: that's how a modern diesel handles its fuel, so the protection counts for more, not less.
This is the one that fools drivers. Myth: "If it starts and drives, there's no damage done." Feed diesel to a petrol engine and it generally won't run, and so the driver stops — and the damage stops with them. Feed petrol to a diesel and it usually starts, ticks over and pulls away like nothing happened — all while its pump wears. Running isn't the same as fine.
Myth: "Add some two-stroke oil and drive the car home." It's an outdated fix for a separate problem. What petrol has diluted remains weakened, and that petrol stays in that tank anyway.
The next start draws petrol back round your pump out of the fuel lines and the filter, where some of that sits once the engine has run. That's why a DIY tank drain does not leave you sorted — a myth. Also, a can of petrol drained at the roadside is truly risky.
How petrol ends up: petrol in a diesel
It is rarely carelessness, and no one does it on purpose. One way only, because of the nozzles: the narrower petrol one slides inside a diesel filler with almost no resistance, while the diesel one mostly will not fit a petrol car. That is how the forecourt makes it straightforward.
When routine and the vehicle stop matching, it takes place. Hire cars, courtesy cars, and vehicles that are new to you. Households running one of each, petrol and diesel. A forecourt you know, but with its pumps laid out differently. Racing for a train at West Ruislip and filling up en route. Years of petrol cars behind you, a diesel Volkswagen Golf in front of you at the forecourt for its first tank — that's when. Throw in a back seat full of kids, a phone call or rain, and habit takes over.
Avoiding petrol in a diesel next time you fill up in Hillingdon
- Not every forecourt in the UK follows green for unleaded and black for diesel, even if most usually do. Read the petrol pump's label; the colour is only a clue.
- Inspect your filler flap. Many vehicles state the fuel type inside the flap or on the cap. Look at it on your first fill in any car you do not know.
- Label your key. In a house with one of each, a coloured fob or a sticker on your diesel's key does more than any amount of meaning to remember.
- Say it before you lift it. On the first fill in a new or hired car, say "diesel" aloud before you take the nozzle off the pump. It seems daft and it works.
- Thinking about something else is when this becomes an easy mistake to make, so put your phone away and keep your mind on the petrol pump.
- A misfuel inhibitor helps, up to a point. Some diesels have a filler built to block a petrol nozzle, and add-on devices exist for cars without one. They are a safety net, not a reason to stop checking the pump.
- Stop the moment you realise. Less petrol inside that tank makes a weaker blend. It does not change what to do next, which is still not to start it.
Hillingdon: already put petrol in a diesel?
Then, there is only a short order of things. Don't switch the ignition on, and don't crank it. If you're still on the forecourt — Esso or anywhere else — ask the staff to help you roll it away from the pump. Then ring 0333 366 0103 and tell us what was put in, about how much, and if it's run.
If it was AdBlue rather than petrol, say so. That's a different issue — corrosion and deposits rather than lost lubrication — and it has its own page for Hillingdon.
Why one petrol in a diesel task around Hillingdon costs more than another
An honest single price doesn't exist here: four situations, four separate jobs. What shifts the cost is mostly which of them you're in. The share matters next, meaning how much of the tank is petrol, and then the location of the vehicle and whether reaching it is safe for a technician.
What went in, how much, and whether it's run — three queries our engineers ask before pricing, not after, for exactly that reason. The answers change a range into a straight figure.
About Hillingdon itself
Hillingdon is a locality in northwest Greater London, situated on the banks of the River Colne at an elevation of around 39 metres. Hillingdon lies approximately 14 miles from central London and is close to nearby places such as North Hillingdon, Ickenham, and Uxbridge. Hillingdon has a population of around 3380 people and is characterised by predominantly terraced housing.
Fuel drain cover across Greater London, Hillingdon included
Hillingdon waits in the UB postcode area, and the vans that answer petrol in diesel jobs there work the spots near it as well — North Hillingdon, Ickenham and Uxbridge among them. Our engineers drain where the car is — your own driveway, a lay-by, a supermarket car park, a forecourt — so it does not have to come to us.
At the pump around Hillingdon, right now?
No position is better: that's where you are. Call, and leave it turned off.