Fleetville: Petrol in a Diesel Car? How Worried to Be
Unstarted? Then less anxious than you probably are. Petrol sitting in a diesel tank does nothing to your motor until something draws it through the fuel system — your ignition priming your pump, your starter, or the drive on its own. So the honest answer to the first question anyone around Fleetville asks, "have I wrecked it?", is normally no. Keep it like that: leave your motor off then ring Petrol in Diesel. The rest of this page explains what petrol really does to a diesel, how to judge how far it has got, and how to make sure it doesn't happen to you again.
Petrol in a diesel: what does it do to the motor?
Two tasks fall to diesel on its journey round a motor. Oiling comes before burning; it does both. Extremely fine clearances go into the injectors and the high-pressure fuel pump, and only the diesel running through keeps their surfaces from grinding together.
Petrol does the first task badly and the second not at all. A pump working on a petrol blend is wearing itself out, since petrol is thinner 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's where the knocking comes.
Taken together, they make clear what shape the trouble takes. The harm is done by movement, not by contact. Where the petrol is only inside the tank, it's a fault of fuel, nothing more. The start of a mechanical one is a pump that has been working on that petrol — and whatever a worn pump sheds moves on with your fuel to the fuel injectors beyond it.
Four situations we see around Fleetville: how bad is petrol in a diesel?
Filled up, never started. The best case there is. Being at a forecourt is what makes this possible: elsewhere, the vehicle has been driven there to begin with. With the petrol kept in that tank alone, it's cleared and rinsed on the spot, and nothing more is needed.
Ignition on, or started for a moment. The fuel system has been bled, and so petrol has left that tank and reached your filter and the fuel lines. Normally little more than draining, rinsing and sorting your filter, so still easy.
Some miles driven, and the pump has spent every one of them labouring on thinned fuel. Miles is only half of it; how hard it was driven counts equally. Either way the work includes your tank, your lines, the filter and fresh fuel through the whole circuit. On the school run to Oakwood Primary School, the miles is small. Getting as far as St Albans, under 3 miles away, makes a very different task — as does any miles on the A1(M), under 3 miles from Fleetville, with the engine running hard all the way.
Driven on until it complained — clattering, smoke, a ragged idle, a dead throttle. The engine is telling you your fuel is no longer behaving like diesel. Pull up where you are — on the verge on Beechwood Avenue, at the kerb, down a side road — and do not move it. The drain and flush-through still come first, and they sort it out: if a car is stopped quickly, lasting damage is very unusual.
Petrol in a diesel myths Fleetville motorists hear
Myth: topping up to full with diesel makes it fine. It does not. A fuller tank of the same mixture is all it gives, since topping up removes nothing. A diesel fuel system doesn't accept petrol by percentage in the way that guidance assumes.
Myth: a modern diesel copes with a bit of petrol. If anything, the reverse. Protection counts more on current 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 fools motorists. Any petrol motor fed diesel usually won't run, and so the motorist stops and the damage stops with them. Nothing looks to have happened when a diesel fed petrol fires up, ticks over and drives away, as it usually will; meanwhile your pump wears. Running is not the same as fine.
Myth: "Add some two-stroke oil and drive it home." It's an old workaround for a different fault. It doesn't put back what petrol has diluted, and the petrol is still inside the tank afterwards.
The next start draws petrol back round the pump out of your lines and the filter, where some of it sits after the motor has run. That is why a DIY tank drain does not leave you sorted — a myth. Draining petrol into a can by the roadside is also truly dangerous.
Why petrol in a diesel takes place at all
Carelessness is seldom the cause, and nobody means to do it. One way only, since of the nozzles: the narrower petrol one slips inside a diesel filler with almost no resistance, whereas the diesel one generally won't fit a petrol vehicle. That's how the forecourt makes it straightforward.
Habit and the car getting out of step is when it occurs. Hire cars, courtesy cars, and cars that are new to you. Households running one of each, petrol and diesel. Your normal forecourt, its pumps suddenly in a different order. A hurried fill on the way to St Albans with a train to catch. The first fill-up in a diesel Renault Megane after years of driving petrol is exactly the moment it takes place. Throw in a back seat full of children, a phone call or rain, and habit takes over.
Next time you fill up in Fleetville: preventing petrol in a diesel
- Check the pump, not the colour. In the UK unleaded handles are usually green and diesel black, but not on every forecourt. The label is what counts.
- Plenty of vehicles state the fuel type inside the filler flap or on the cap, and so check it on the first fill in a vehicle you don't know.
- One of each in the home? Label the key to the diesel — a coloured fob, a sticker — because intending to remember isn't enough.
- Before the nozzle leaves the pump the first time you fuel a hired or new car, say "diesel" out loud. Daft, yes, but it works.
- Thinking about something else is when this becomes an easy mistake to make, and so put your phone away then keep your mind on the pump.
- A misfuel inhibitor helps, up to a point. Some diesels come with a filler built to refuse a petrol nozzle, and add-on devices exist for motors without one. They are a safety net, not a reason to stop checking the pump.
- As soon as you notice, stop: less petrol inside the tank makes a weaker mixture. What to do next does not change, though — still don't start it.
Already put petrol in a diesel around Fleetville?
Then the order of things is short. Leave it unstarted, with the ignition off as well. Yet at the forecourt, at Morrisons or anywhere else? Ask the staff to help you roll the car away from the pump. Then call 0333 366 0103 and tell us what got in, about how much, and whether it's run.
If it was AdBlue rather than petrol, say so. That's a separate problem — corrosion and deposits instead of lost lubrication — and it has its own page for Fleetville.
What makes one Fleetville petrol in a diesel job cost more than the next
The four situations above are four different jobs, so no single quote for this would be fair. What moves the cost is chiefly which of them you're in. Two things follow that: the petrol that went in as a proportion of what the tank holds, then the place the vehicle is in and whether a van can get to it safely.
What was put in, how much, and if it's run — three queries our engineers ask before quoting, not after, for precisely that reason. A range turns into a straight figure when those answers are in.
About Fleetville
Fleetville is a suburban area located near St Albans in Hertfordshire, sitting at an elevation of around 102 metres in the inland landscape of the Eastern region. Fleetville is characterized by its predominantly semi-detached housing stock and is situated close to nearby places such as Marshalswick and Bernards Heath. Fleetville is also within commuting distance of London, approximately 18.8 miles away. Fleetville has a population of around 7238 residents.
Fuel drain cover in Fleetville and across Hertfordshire
Fleetville sits in the AL postcode area, and the vans that answer petrol in diesel jobs there work the spots around it as well — Marshalswick, The Camp and Bernards Heath among them. A forecourt, a supermarket car park, a lay-by or your own driveway are all spots our technicians drain, and your car does not need to come to us.
Fleetville: still at the petrol pump?
The best position there is, then — that's where you are. Turned off it stays; then call.