Thornton: Petrol in a Diesel Car? How Worried to Be
Probably less than you are now — as long as nobody has started it. Everyone in Thornton begins with "have I wrecked it?", and the honest answer is normally no: petrol resting in the tank of any diesel remains harmless until priming, cranking or driving pulls it into the system. Petrol in Diesel is who to ring, with the motor left off, and so it remains that way. Read on for three things: the effect petrol has inside a diesel engine, the clues of how far it has got, and ways to make sure you don't repeat it.
Petrol in a diesel: what does it do to your engine?
On its way through a motor, diesel does two jobs. Before it ignites, it protects — then it ignites. Your high-pressure pump and your injectors are built to extremely fine clearances, and your diesel passing through them is what stops those surfaces from wearing down against one another.
Of these two jobs, petrol manages the first poorly and the second not at all. The clattering comes from petrol being made not to ignite when compressed, which is exactly the reverse of what a diesel needs. On top of that it is runnier than diesel, it strips away the lubrication the system depends on, and any pump working on that mix is wearing itself.
Seen together, they make clear the shape the problem takes. It's movement that causes the damage, not contact. Petrol in a tank is a fuel issue. Whatever a worn pump sheds travels on, carried by the fuel, into the fuel injectors downstream, which is why a pump that has worked on the petrol is where a mechanical issue starts.
How bad is petrol in a diesel? Four scenarios we see in Thornton
Fuelled but not once started — the best it gets. Only your tank has petrol in it, so the task is emptying the tank and purging the system where the vehicle stands. This situation can only truly happen on a forecourt: anywhere else, the car got there by being driven.
A brief spell of running, or just the ignition on. Your system has been primed, so petrol has left that tank and reached the filter and the lines. Usually little more than clearing, flushing and sorting your filter, and so still easy.
Those few miles on the road were the pump working on fuel diluted by petrol throughout. How hard the vehicle was driven counts as much as how far, and this work covers your tank, your lines, the filter and clean fuel through the entire system. Short trips, such as the school run to St William of York Catholic Primary School, are one matter. Driving as far as Liverpool, under 10 miles away, makes a very different task — as does any miles on the M58, under 3 miles from Thornton, with the engine running hard all the way.
Clattering, a lumpy idle, smoke, a throttle gone soft: driven until it complained. The engine is telling you your fuel is no longer behaving like diesel. Pull up wherever you are — the verge on Holgate, a lay-by, a side street — then leave the vehicle there. A car stopped quickly very seldom has permanent damage, since the drain and the flush-through, which still come first, deal with it.
Petrol in a diesel myths Thornton motorists hear
"Top it up the rest of the way with diesel and it will be fine" — a myth. It won't. A bigger tank of the same mix is all it gives, because topping up takes out nothing. The idea behind the advice — that diesel fuel systems tolerate petrol by percentage — is wrong.
"Current diesels can handle a little petrol" — a myth, and nearer the reverse. Lubrication counts more on newer diesels, not less, because their fuel runs through more precise parts at higher pressure.
One myth that catches drivers off guard: if it starts and drives, it must be unharmed. A petrol engine fed diesel usually will not run, so the driver stops and the damage stops with them. Feed petrol to a diesel and it usually fires up, idles and pulls away like nothing has happened — all the while its pump is wearing. Running is not the same as fine.
An outdated workaround for a different fault is behind this one. Myth: "Add some two-stroke oil and drive it home." It doesn't put back what petrol has weakened, and that petrol is still in your tank after that.
The next start draws petrol back round the pump out of the lines and the fuel filter, where some of that sits once the motor has run. That is why a DIY tank drain does not leave you sorted — a myth. Also, a can of petrol drained by the roadside is genuinely risky.
How does petrol in a diesel take place?
A careless moment is rarely the cause, and nobody means to do it. The forecourt makes it easy: the petrol nozzle is the smaller of the two, and it slips into a diesel filler with almost no resistance, while a diesel nozzle mostly will not go into a petrol motor at all. So the mistake runs one way.
Habit and your car getting out of step is how it occurs. Any vehicle that is new to you — hired, on loan as a courtesy car, or brand new. Two motors on one driveway, one petrol, one diesel. Your ordinary forecourt, its pumps suddenly in a different order. A train to catch, and a hurried fill en route to Blundellsands & Crosby. Years of petrol cars behind you, a diesel Volkswagen Tiguan 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 the hand takes over.
Thornton people: how to prevent petrol in a diesel next time
- A green handle for unleaded and black for diesel is usual in the UK — yet not on each forecourt. Go by the label on the petrol pump, not the colour.
- In a motor you don't know, look inside the flap over your filler or at the cap before your first fill: many motors state the fuel there.
- Good intentions count for less than a sticker or a fob in a bright colour on your diesel's key when a household has one of each. So label it.
- It sounds silly and it does the trick: on the first fill in a new or hired car, say "diesel" out loud before you take the nozzle off the petrol pump.
- Thinking about something else is when this becomes an easy mistake to make, and so put the phone away and keep your mind on the pump.
- A misfuel inhibitor helps, up to a point. Some diesels have a filler built to reject a petrol nozzle, and add-on devices are available for motors without one. They are a safety net, not a reason to stop reading the pump.
- Stop the moment you realise. Less petrol in the tank makes a weaker mix. It does not change what to do next, which is still not to start the vehicle.
Thornton: already put petrol in a diesel?
Then the order of things is short. Don't turn the ignition on, and don't crank it. The attendants at the forecourt — whether at Texaco itself or wherever you filled up — will normally help roll it away from the pump if you ask. Call 0333 366 0103 next, with three facts — your fuel, the approximate quantity, and if it has run.
AdBlue, not petrol? Then tell us. Corrosion and deposits, not lost protection, make it a separate fault — Thornton has a page just for it.
What makes one Thornton petrol in a diesel job cost more than the next
An honest single price doesn't exist here: four scenarios, four separate tasks. The scenario itself does most of the work of moving the cost. The ratio counts next, meaning how much of your tank is petrol, followed by the location of your car and whether reaching it is safe for a van.
What got in, how much, and if it's run — three queries our engineers ask before quoting, not after, for precisely that reason. Given the replies, you get a straight figure instead of a range.
About Thornton itself
Thornton is a suburban area in Merseyside, situated near the coast and approximately 6 miles from Liverpool. Thornton has a relatively low elevation of 22 metres and is surrounded by other local places such as Moor Park and Lunt. Thornton is characterised by its predominantly semi-detached housing stock, reflecting the typical residential development of the region.
Across Merseyside and in Thornton: fuel drain cover
Moor Park, Lunt and Homer Green are among the locations around Thornton that the same teams work, answering petrol in diesel calls across Thornton's L postcode area. The car does not need to come to us: our technicians drain on a forecourt, in a supermarket car park, in a lay-by or on your own drive.
In Thornton and still at the pump?
Nothing beats it: that's where you now are. Keep it switched off, and ring.