Drumchapel: Petrol in a Diesel Car? How Worried to Be
Provided it hasn't been started, worry far less than you likely are. "Have I ruined it?" is the first question anyone around Drumchapel asks, and the honest answer is generally no, because petrol resting in a diesel tank harms nothing till it is drawn through your fuel system — by ignition priming, by the starter, or by being driven. Petrol in Diesel is who to call, with your engine left off, so it stays that way. What petrol actually does to a diesel, how to gauge how far it has gone, and how to keep it from happening a second time: that is the rest of this page.
Petrol in a diesel: what does it do to your engine?
Two tasks fall to diesel on its route through a motor. Oiling comes before burning; it does both. What stops the surfaces inside your high-pressure pump and the injectors from wearing against one another is your diesel passing through them — they're made to extremely fine clearances.
The second job petrol does not do at all, and the first it does poorly. A pump running on a petrol mixture is wearing itself out, because petrol is runnier than diesel and strips out the lubrication the fuel system depends on. Petrol is also made to resist igniting under compression — the opposite of what a diesel wants from its fuel — and that's where any clattering comes.
Seen together, they show what shape the issue has. Contact does not do the harm — circulation does. Any tank with petrol in it is a fuel problem. Whatever a worn pump sheds goes on, borne by your fuel, into the fuel injectors further along, which is why a pump that has worked on the petrol is where a mechanical fault begins.
Four scenarios our technicians see around Drumchapel: how bad is petrol in a diesel?
Fuelled up, never started. The best case there can be. Only your tank has petrol in it, so the job is clearing the tank and purging the system where your car stands. This scenario can only truly occur at a forecourt: anywhere else, the vehicle got there by being driven.
Started for a moment, or just your ignition on. Your system has been primed, so petrol has left your tank and got to the filter and the fuel lines. That's generally still an easy job — a drain, a flush, and the filter seen to.
The pump now spent a couple of miles on diluted fuel — that is what driving it meant. The work is the tank, the lines, your filter and fresh fuel through the whole system, and how hard your car was driven counts as much as how far. On the school run to the local primary school, the distance is short. Driving as far as Glasgow, under 10 miles away, makes a very different job — as does any mileage on the M8, under 3 miles from Drumchapel, with your engine running hard the whole time.
Driven till it protested. Knocking, a lumpy idle, smoke, a throttle that has gone soft. The engine is telling you the fuel is no longer acting like diesel. Pull up on the spot — on the verge on Hecla Avenue, at the kerb, down a side road — and do not move it again. A car pulled over quickly very seldom has permanent damage, as the fuel drain and the flush-through, which still go first, take care of it.
Petrol in a diesel stories Drumchapel drivers hear
Myth: "Fill it the rest of the way with diesel and it'll be fine." It will not. Topping up takes out nothing; it gives you a fuller tank of the same mix. A diesel fuel system doesn't tolerate petrol by percentage in the way that advice assumes.
Myth: a newer diesel copes with a bit of petrol. Rather, the reverse. Lubrication counts more on newer diesels, not less, since their fuel runs through smaller components at higher pressure.
This is the one that catches people. Myth: "If it starts and drives, there is no damage done." A petrol engine fed diesel usually won't run, and so the driver stops and the damage stops with them. Feed petrol to a diesel and it usually fires up, ticks over and pulls away as if nothing has happened — all while its pump wears. Being able to run isn't proof of being fine.
Not so: a two-stroke additive lets you to drive home. It is an old fix, supposed for another fault. What petrol has thinned remains thinned, and the petrol remains in that tank regardless.
Once the motor has run, part of that petrol sits in the filter and the fuel lines, not the tank — and the next start pulls it straight back through the pump. So the myth "drain the tank yourself and you are sorted" doesn't stand up. Also, a can of petrol drained at the kerbside is genuinely risky.
Why petrol in a diesel happens so easily
No one does it on purpose, and it's seldom carelessness. One way only, since of the nozzles: the narrower petrol one slides inside a diesel filler with almost no resistance, whereas the diesel one mostly won't fit a petrol motor. That is how the forecourt makes it straightforward.
When habit and the car stop matching, it takes place. Any motor that's new to you — a hire car, on loan as a courtesy car, or just bought. Two vehicles on one driveway, one petrol, one diesel. The pumps in a different order on a familiar forecourt. A train to catch, and a rushed fill en route to the nearest station. Precisely the moment it occurs: after years of driving petrol, a driver fills a diesel Volkswagen Golf for the first time. With rain, a call arriving, or children to deal with, the hand just does what it always has.
How to prevent petrol in a diesel on your next fill-up around Drumchapel
- Not every forecourt in the UK follows green for unleaded and black for diesel, though most usually do. Read the pump's label; the colour is only a clue.
- Inspect your filler flap. Plenty of vehicles state the fuel type inside the flap or on the cap. Look at it on your first fill in a vehicle you do not know.
- A coloured fob or a sticker on your diesel's key achieves more than any amount of meaning to remember, for a household with one of each.
- It sounds daft and it works: on your first fill in a new or hired car, say "diesel" aloud before you lift the nozzle off the petrol pump.
- Whilst you're thinking about something else, this is an easy mistake to make — so put the phone away.
- Up to a point, a misfuel inhibitor helps: some diesels have a filler designed to block a petrol nozzle, and aftermarket devices are available for the rest. Treat it as a backstop, then keep checking the pump.
- Noticing it mid-fill? Stop there and then. A thinner mix follows from less petrol in that tank, yet your next step stays the same: do not fire it up.
Already put petrol in a diesel in Drumchapel?
The order of things is brief, then. Never start the car, and don't turn the ignition on. The staff at the forecourt — whether at Sainsbury's itself or wherever you filled up — will usually help roll it away from the pump if you ask. What went in, about how much, and if it's run: tell us those when you call 0333 366 0103.
Say so if it was AdBlue rather than petrol: it is a separate issue, with its own page for Drumchapel, because AdBlue brings corrosion and deposits rather than lost protection.
One petrol in a diesel task in Drumchapel costs more than another. Why?
The four situations above are four different tasks, so no single price for this would be honest. The scenario itself does most of the work of moving the cost. Where the vehicle is counts too, and whether a technician can safely reach it, after the proportion of petrol to what your tank takes.
That is why our engineers ask three queries before costing instead of after: what went in, how much, and if it's run. Those answers change a range into a straight figure.
About Drumchapel itself
Drumchapel is a suburban area situated on the River Clyde, with a relatively low elevation of 22 metres. Drumchapel lies on the northwestern outskirts of Glasgow, approximately 6 miles from the city centre. Drumchapel is characterized by its predominantly flat-type housing and is located near other nearby places such as Old Drumchapel and Drumry. Drumchapel has a population of around 4582 residents.
Drumchapel and Glasgow City: where our fuel drain cover reaches
Old Drumchapel, Linnvale and Drumry are among the places around Drumchapel that the same vans work, answering petrol in diesel call-outs across Drumchapel's G postcode area. Our engineers drain wherever the 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 petrol pump in Drumchapel?
No position is better: that is where you now are. Turned off it stays; then phone.