How Do I Drain Petrol Out Of A Diesel Renault Megane?

Most diesel engines will tolerate a small amount of petrol so you don't have to get every last drop of diesel out. Rigging up a syphon or a hand pump should be enough. When you have gotten as much petrol as you can out fill the tank with diesel, what every is left of the petrol will mix well with the diesel.

If you ran the engine till it stopped (sucked up some petrol) then you should purge the injection pump before you try and start the engine again.

As long as there is not too much Petrol you should be ok if you just fill the tank with Diesel. If there is less then 1/4 of the tank with Petrol then the Diesel mix should run the engine just not as well as normal.

It has to be siphoned out,if can't get a hose in through gas filler spout,it may need to be unclamped at the tank and have filler spout out of the way to get a hose in to siphon