An occasional series explaining how to do things. Equipment: Jerry can, garden hose, Stanley knife, 2 litres of Dr Pepper, mobile phone (two minimum), mates who, unlike you, know their arse from their elbow.
Step-by-step guide Siphoning fuel from the tank of your car requires first that you create the need to carry out the siphoning in the first place. Here's my step-by-step guide to the whole process.
1. Arrive at filling station.
2. For some reason unknowable, opt to fill diesel tank with unleaded petrol.
3. Phone your mate Pat, who knows all about cars, to find out how much of a clusterfuck you've got yourself into. This will turn out to be quite a big one.
4. Phone breakdown sevice provider to discover astronomical cost of getting tank drained.
5. Highhandedly declare "Sod that" and elect to drain tank yourself.

6. Get shouted at over intercom for using mobile phone on forecourt.
7. Push car off forecourt.
8. Calculate quantity of diesel/unleaded mix in tank. Reason that if you can get most of that off, you're home and dry.
9. Repair to local Halfords to buy jerry can and amusingly named 'jerk siphon'.
10. Discover that siphon doesn't work because your car has an 'anti-siphon device' a.k.a. a small metal bar across the fuel inlet.
11. Swear a bit.
12. Repair to local Homebase to buy reinforced hose and Stanley knife.
13. Suck unleaded from tank. Get really good mouthful of the stuff. Repeat endlessly.
14. Conclude that this fucking siphoning lark doesn't work.
15. Decide a slope is required to aid siphoning. Push car down slope.
16. Decide car is wrong way round. Push it back up the slope. This should ideally take about half an hour and involve at least 30 people going past without a single one offering to help.
17. Push car back down slope facing the other way.
18. Suck unleaded from tank. Get really good mouthful of the stuff. Repeat endlessly.
19. Conclude that this fucking siphoning lark absolutely doesn't work.
20. Swear a lot. Hit things.
21. Ideally, it should start raining about now in order to properly heighten the misery.
22. Concede defeat. Phone breakdown service provider and eat humble pie.
23. It is crucial at this stage to have selected an inept breakdown service provider, for reasons that will become apparent.
24. Sit in car feeling sorry for yourself. At this point, your mobile phone should also stop working.
25. Start to suspect you may be getting hypothermia.
26. After waiting 45 minutes past deadline for breakdown service provider to arrive, decide you might as well give it another go.
27. Push about 10 feet of garden hose into the tank.
28. Suck unleaded from tank. Get really good mouthful of the stuff. Repeat endlessly.
29. Discover that Dr Pepper actually masks the flavour of petrol.
30. Miraculously witness the siphon start to work. Be at a loss to explain why.
31. At this point, your mate Harvey should pitch up with dinner and a working mobile.
32. Make mental note to nominate Harvey for beatification.
33. Estimate that you have all but a couple of litres of fuel off the tank. Start to feel hopeful.
34. Speak on the phone to a very helpful Swedish engineer who you have never met before, but who your wife has tracked down.
35. Conclude, based on his advice, that you're going to gamble and fill up with diesel. If you're right, you'll drive away. If you're wrong, you're looking at a bill of £1,000 plus for tank draining, wasted fuel and knackered fuel pump.
36. Back yourself. Phone breakdown service provider and tell them to poke it.
37. Push car back to pump with Harvey's help.
38. Fill the tank. It's a 60 litre tank and you'll need to have less than 5 litres of unleaded in there if you stand a hope of getting away with it.
39. Breathe huge sigh of relief as pump cuts out at 58.5 litres.
40. Successfully start car.
41. Experience sense of triumph, despite having spent 5 hours soaked inside and out with petrol and half frozen to death just because you were chump enough to pull an amateur trick like filling your car with the wrong fuel.
42. Go to pub and drink.