Drain home heating oil tank

My Mum is changing from home heating oil to kerosene. She is getting a fill next week and when she asked about getting the oil drained from the tank she was told she would have to do it herself. So that's where I come in! There is about 6 inches left at the bottom of the tank and it's a plastic tank (so pretty lightweight to tip if I have to). So my questions

1) Is it important to get every last drop out?
2) Will a siphon work? I don't know if there is a drain cock (I suspect not)
3) Has anybody else done this, any tips?

You may wish to double check this but your burner should pretty much burn both products off. There is probably no need to drain it for the 20 or 30 litres in the bottom.

You will have to adjust your burner in any event to take account of the different characteristics of kerosene.

what is currently in the tank? Is it diesel?
I always throw in 25/30 litres of diesel into my kerosene fill, the diesel will lubricate the heat pump and thus will last longer.. Believe it or not I also throw the used oil from the car and jeep into it as well…as it will be well diluted by the time it gets to the boiler…waste not want not!

you can buy in a 50/50 mix but you may have to adjust your burner....

She is getting a new stove installed (which involves a new line being run from the tank) and getting a new burner (as the old one was on it's last legs). Apprently the stove needes kerosene as it burns much cleaner. I think we will have to drain it to install the new line and the new equipment.