5 litres of petrol in my diesel?

No amount of petrol in a diesel is an amount we will call safe, not one litre and not five. Don't start the engine, call us on (08) 7083 9699, and we'll come to you and drain it.

It's not the answer anyone wants when only a few litres went in before they noticed. So here's the reasoning behind it and what to do in the next few minutes.

If the engine hasn't been started, the petrol is sitting in the tank. It hasn't reached the high pressure fuel pump, common rail or the injectors yet. That's the best spot you can be in, and it's why we push so hard on not starting it. Don't switch the ignition on either. On many cars that starts the fuel pump. Wrong fuel can move through the system before the engine starts.

What if it was 4 or 5 litres?

Same answer. Whether it's 1, 4, 5 or 10 litres, there's no amount we'll put our name to as safe.

A small amount still gets drained. One recent job was a Hiace work van at Hallett Cove, caught mid fill at the pump. We drained it right there at the servo.

How much petrol can damage a diesel engine?

Nobody can give you an honest number. A diesel engine relies on the fuel itself to lubricate its fuel system components. Petrol does the opposite.

Petrol cuts that lubrication. It acts as a solvent and strips it away. Metal parts can rub together and shed particles. Those particles can damage the rest of the fuel system. That's why even a small splash of petrol in a diesel tank means a drain. There's more on how it plays out on our petrol in a diesel page.

Running it can damage the fuel system. That can mean a costly repair. If you've already started it, stop somewhere safe and switch it off. Don't restart it.

Why won't you name a safe amount?

Because we'd be guessing, and you'd be the one paying if the guess was wrong. Three reasons:

• Nobody can see into the tank. There's no telling exactly how much went in or even if what went in was clean fuel. It could have been contaminated, leading to damage later on down the line.
• The pump doesn't know it's only a little. Diesel lubricates the high pressure pump, injectors and other fuel components. Petrol cuts that lubrication. They all run on whatever mix comes out of the tank.
• It depends on the situation. How long the vehicle has been run matters too. We won't guess at the damage from the number of litres.

So everyone gets the same advice, whatever the amount. Don't run it. Get it drained.

What if it's only a little diesel in a petrol car?

It still gets drained, even if it was only a splash. A petrol engine lights its fuel with a spark, so it can't burn diesel properly. More on that in can you dilute petrol with diesel.

What should I do right now?

1. Don't start the engine. Don't switch the ignition on to check the gauge either. On a lot of cars that primes the fuel system.
2. Tell the servo attendant what's happened. It happens often so they know exactly how to deal with this situation.
3. Don't top up with diesel to dilute it. Here's why.
4. Call (08) 7083 9699. Tell us the car, the suburb and which way the mix up went. We quote you on the phone before we come.

Already started it, or driven off before you noticed? Stop somewhere safe. Switch it off. Don't restart it. Let us know when you ring. We can still do the job, there are just a few more steps. There's more in how far you can drive on petrol in a diesel.

We come to you anywhere around Adelaide. At the servo, at home, at work or on the side of the road. We drain the wrong fuel, clean the tank, flush the lines, prime the fuel system, get the vehicle started, conduct a full vehicle scan and post service inspection. The old fuel is disposed of under our EPA licence. We handle the fuel side only. Suspected internal damage is referred to a workshop. Every job is covered by our No fix, no fee guarantee.

If you're standing at the pump reading this and the engine hasn't been started, you're in the best spot you can be. Leave it off and call (08) 7083 9699.