Cathkin: Petrol in a Diesel Car? How Worried to Be
Less than you likely are, if it hasn't been started. Petrol sitting in a diesel tank does nothing to the motor until something draws it through your fuel system — your ignition priming your pump, the starter, or the drive on its own. So the fair answer to the first query everyone around Cathkin asks, "have I ruined it?", is usually no. Keep it that way: leave the engine off and phone Petrol in Diesel. The rest of this page explains what petrol actually does to a diesel, how to tell how far it has got, and how to make sure it doesn't happen to you again.
Your engine and petrol in a diesel: what happens
Diesel has two tasks on its way through an engine. It lubricates first, and after that does it burn. The high-pressure pump and the fuel injectors are designed to extremely fine clearances, and your diesel passing through them is what stops those surfaces from grinding against one another.
The second task petrol doesn't do at all, and the first it does poorly. Being less viscous than diesel, petrol strips out the protection a fuel system needs, leaving a pump on that mixture wearing itself. It is equally made to resist igniting under compression — the opposite of what a diesel needs — which is where you hear the knocking.
Combined, those leave the shape of the issue plain. Not contact but circulation is what causes the harm. Where the petrol is only inside that tank, it's a fault of fuel, nothing more. After your pump has been working on that petrol, a mechanical fault has started: whatever is shed by a pump that is wearing is carried downstream to your injectors with the fuel.
Four situations our engineers see around Cathkin: how bad is petrol in a diesel?
Filled but not once started — the best it gets. On a forecourt, and really only there, that petrol is still limited to your tank — since everywhere else your car was driven to get to it. The job is draining and purging on the spot.
Started for a moment, or only your ignition on. With your system primed, your lines and filter already hold petrol that came from the tank. Still usually easy: drain, flush, and the filter seen to.
A couple of miles driven, and your pump has spent each of them working on thinned fuel. The work is that tank, your lines, your filter and fresh fuel through the entire circuit, and how hard the vehicle was driven matters as much as how far. The school run to the local primary school is one matter. Getting as far as Glasgow, under 5 miles away, makes a very different job — as does any miles on the M74, under 3 miles from Cathkin, with your engine running hard the whole time.
Rattling, an uneven idle, smoke, a throttle gone soft: driven until it complained. That's your engine telling you its fuel has stopped behaving like diesel. Stop on the spot — on the verge on Glencoe Road, at the kerb, down a side road — and don't move it. A vehicle pulled over quickly very seldom has permanent damage, as the drain and the flush-through, which still come first, sort it out.
What Cathkin drivers get told about petrol in a diesel — and the myths in it
False: topping up to full with diesel makes it fine. It does not. A bigger tank of the same mixture is all it gives, since topping up removes nothing. That guidance presumes a diesel fuel system tolerates petrol by percentage. It does not.
Myth: "A current diesel can cope with a bit of petrol." If anything, the opposite. A newer diesel runs its fuel through smaller parts at higher pressure, which makes the protection matter more, not less.
Myth: "If it starts and drives, there's no harm done." This is the one that fools motorists. Feed diesel to a petrol engine and it normally 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, which it usually does; meanwhile the pump wears. Being able to run isn't the same as being fine.
Myth: "Add some two-stroke oil and drive it home." It is an old workaround for a separate fault. It doesn't put back what petrol has diluted, and the petrol is still in the tank later.
The next start sends petrol back round the pump from the fuel lines and the fuel filter, where some of that ends up after the engine has been run. That is why a DIY tank drain does not leave you sorted — a myth. Besides, petrol cleared into a can by the road is genuinely risky.
Petrol in a diesel: how does it occur?
Carelessness is seldom the cause, and nobody means to do it. A diesel nozzle mostly will not go into a petrol vehicle, but the smaller petrol nozzle goes into the filler of a diesel almost without resistance — so forecourts make this one error straightforward, and just in that direction.
The moment routine stops matching your car is the moment it takes place. A new vehicle, a hire car or a courtesy car. Two vehicles on one driveway, one petrol, one diesel. Your normal forecourt, its pumps now in a different order. Racing for a train outside Burnside and filling up en route. A new-to-you diesel Volkswagen Passat, its first fuelling, and a motorist used to petrol: precisely when it takes place. Add a back seat full of children, a phone call or rain, and habit wins.
Avoiding petrol in a diesel next time you fill up around Cathkin
- Check the petrol pump, not the colour. In the UK unleaded handles are usually green and diesel black, but not on each forecourt. The label is what matters.
- Many motors state the fuel type inside your filler flap or on the cap, and so check there on your first fill in a motor you don't know.
- Mark the key. In a household with one of each, a coloured fob or a sticker on your diesel's key does more than any amount of intending to remember.
- Say it before you lift it. On your first fill in a new or hired car, say "diesel" aloud before you lift the nozzle off the pump. It seems silly and it does the trick.
- Mistakes like this are straightforward to make whilst your mind is on something else, so the phone goes away.
- Some diesels come with a filler designed to reject a petrol nozzle, and devices you can add are available for cars without one. Such an inhibitor helps up to a point — as a backstop, not a reason to stop checking the pump.
- Noticing it halfway? Stop there and then. A weaker mixture follows from less petrol inside your tank, yet your next step remains the same: don't start the vehicle.
Petrol already in a diesel around Cathkin? Start here
Short and simple, then, is the order of things. Leave it unstarted, with your ignition switched off too. The staff on the forecourt — whether at Esso itself or wherever you filled up — will normally help push it away from the petrol pump if you ask. What went in, about how much, and if it's run: tell us those when you phone 0333 366 0103.
Corrosion and deposits form the trouble with AdBlue, whereas petrol means lost protection. So if it was AdBlue, say so — and read its own Cathkin page.
One petrol in a diesel job around Cathkin costs more than another. Why?
The four scenarios above are four different jobs, so no single price for this would be honest. What shifts your cost is mostly which of them you're in. After that it's the proportion — how much petrol went in against how much the tank holds — and then where the vehicle is and whether a van can get to it safely.
Three questions come first, before any quote, instead of after — what went in, how much, has it run — and that is the reason. The answers change a range into a straight figure.
About Cathkin
Cathkin is a village situated on the riverside in South Lanarkshire, with a mix of flat housing and other residential properties, lying approximately 110 metres above sea level. Cathkin is located near several other communities, including Springhall, Fernhill, and High Burnside, and is close to the city of Glasgow, which is about 4.3 miles away. Cathkin has a population of around 3978 people and is part of the wider Glasgow urban area. Cathkin sits in a scenic area, with the River Clyde flowing nearby.
Fuel drain cover in Cathkin and across South Lanarkshire
Petrol in diesel calls in Cathkin — part of the G postcode area — go to vans that likewise cover the spots about it, Springhall, Fernhill and High Burnside included. A forecourt, a supermarket car park, a lay-by or your own drive are all locations we work, and the vehicle does not need to move to us.
At the petrol pump around Cathkin, right now?
No position is better: that's where you are. Keep it off. Phone.