How Worried Should You Be? Petrol in a Diesel Car in Mill Yard
Less than you probably are, if it hasn't been started. Till your ignition primes your pump, the starter cranks, or your vehicle is driven, petrol in a diesel tank just sits there and does nothing. Which means the truthful reply to that first Mill Yard question — "have I wrecked it?" — usually no. Leave your engine off and call Petrol in Diesel — that is how you keep it that way. The remainder of this page sets out what petrol actually does to a diesel, how to judge how far it has got, and how to make sure it does not happen to you a second time.
What petrol in a diesel does to your engine
On its way through a motor, diesel does two jobs. It ignites, and before it burns it protects. Very fine tolerances are built into the fuel injectors and your high-pressure pump, and only the diesel running through keeps those surfaces from grinding together.
Poorly at the first, not at all at the second: that is petrol. A pump running on a petrol blend is wearing itself out, because petrol is runnier than diesel and strips out the protection your 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 is where the rattling comes.
Taken together, they show the shape the problem takes. Not contact but circulation is what does the harm. All a tank with petrol in it amounts to is a fuel fault. After the pump has been labouring on that petrol, a mechanical problem has begun: whatever is shed by a pump that is grinding is carried downstream to the fuel injectors with your fuel.
How bad is petrol in a diesel? Four situations our engineers see around Mill Yard
The best case there is: filled up, never started. Being at a forecourt is what makes this the case: elsewhere, the car has been driven there to begin with. With that petrol held in the tank alone, it's cleared and cleaned on the spot, and nothing more is needed.
Ignition on, or started for a second. Your system has been bled, and so petrol has left the tank and got to your filter and your lines. Drain, flush, deal with the fuel filter: still usually easy.
A few miles driven, and your pump has spent each of them labouring on diluted fuel. Miles is only half of that; how hard it was driven matters equally. Either way the work runs to the tank, your lines, your filter and clean fuel through the entire circuit. Short trips, such as the school run to Knotty Ash Primary School, are one matter. Very different again: a trip to Liverpool, under 5 miles away, or some miles on the M62, under a mile from Mill Yard, where your engine never stopped working hard.
Clattering, an uneven idle, smoke, a throttle gone soft: driven until it complained. The fuel is not behaving like diesel any more, and your engine is saying so. Stop where you are — on the verge on The Greenway, at the kerb, down a side road — and don't move it. What comes first is still the fuel drain and flush-through, and that takes care of it, with long-term damage very unusual if a car is pulled over soon.
Stories Mill Yard 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 when you top up — that tank simply holds more of the same blend. That advice supposes a diesel fuel system handles petrol by percentage. It doesn't.
Not so: a newer diesel copes with a bit of petrol. If anything, the opposite. Protection matters more on modern diesels, not less, since their fuel runs through smaller parts at higher pressure.
Myth: "If it starts and drives, there's no harm done." This is the one that catches drivers. Diesel in a petrol motor usually leaves a motor that will not run: the motorist stops, and so does the harm. Feed petrol to a diesel and it generally fires up, ticks over and pulls away like nothing happened — all the while its pump wears. Fine and running aren't the same at all.
Myth: "Add some two-stroke oil and drive it home." It is an old workaround for a separate problem. It does not put back what petrol has weakened, and that petrol is still inside that tank afterwards.
If the engine has run, part of the petrol is in your filter and the lines, not the tank — and your next start pulls it straight back through your pump. So the myth "drain that tank yourself and you're sorted" does not stand up. Also, a can of petrol filled by the roadside is genuinely dangerous.
How does petrol in a diesel happen?
On purpose? Never. Through carelessness? Rarely, if ever. One way only, since of the nozzles: the slimmer 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 easy.
Routine and the vehicle getting out of step is how it takes place. A new car, a hire car or a courtesy car. Households running one of each, petrol and diesel. A well-known forecourt with the pumps in a different order. A train to catch, and a rushed fill en route to Broad Green. Years of petrol motors behind you, a diesel Volkswagen Tiguan in front of you at the forecourt for its first tank — that's when. Throw in rain, a phone call or a back seat full of children, and the hand repeats what it has always done.
Mill Yard motorists: how to avoid petrol in a diesel next time
- The label is what counts, and 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.
- In a motor you don't know, look inside the flap over your filler or at the cap before your first fill: many cars state the fuel there.
- Good intentions do less than a sticker or a fob in a bright colour on your diesel's key if a household has one of each. So mark it.
- Say it before you lift it. On the first fill in a new or hired car, say "diesel" out loud before you take the nozzle off the pump. It sounds silly and it does the trick.
- 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.
- Some diesels have a filler built to reject a petrol nozzle, and devices you can add exist for cars without one. Such an inhibitor helps up to a point — as a safety net, not a reason to stop reading the petrol pump.
- Less petrol makes a thinner blend, so stop the moment you realise — while remembering that your next stage is unchanged. It is still not to crank it.
Put petrol in a diesel in Mill Yard already?
Then the order of things is short. Starting it is out, and so is turning on your ignition. If you are still on the forecourt — Sainsbury's or anywhere else — ask the attendants to help you roll the vehicle clear of the pump. Then phone 0333 366 0103 and tell us what went in, roughly how much, and whether it has run.
If it was AdBlue and not petrol, say so. That is a separate issue — corrosion and deposits and not lost lubrication — and it has its own page for Mill Yard.
What makes one Mill Yard petrol in a diesel task cost more than the next
There is no honest single quote for this, since the four scenarios above are four separate tasks. Which of them you are in is mostly what moves your cost. Two things follow that: the petrol that was put in as a proportion of what the tank holds, then the spot the vehicle is in and whether our van can reach it safely.
What went in, how much, and if it's run — three questions we ask before quoting, not after, for exactly that reason. Given the answers, there is a straight figure instead of a range.
About Mill Yard
Mill Yard is a suburban area located inland in Merseyside, with an elevation of 32 metres, and is situated approximately 3.8 miles from Liverpool. Mill Yard forms part of the larger urban landscape surrounding Liverpool, with nearby places including Knotty Ash, Swanside, and Dovecot. Mill Yard is characterised by its predominant semi-detached housing stock, which reflects the typical residential development patterns of the North West region. Mill Yard has a population of around 7165 residents, according to approximate estimates.
Fuel drain cover across Merseyside, Mill Yard included
Petrol in diesel jobs in Mill Yard — part of the L postcode area — go to teams that likewise cover the locations around it, Knotty Ash, Swanside and Dovecot among them. Our engineers drain wherever your car is — your own driveway, a lay-by, a supermarket car park, a forecourt — so it does not have to come to us.
Still at the pump around Mill Yard?
Then, you couldn't be in a better position. Switched off it stays; then ring.