I have a Skoda Superb 2.0 diesel, 2005-6. Needing to save money, I can buy a biodiesel kit and buy the used filtered oil. I have a spare garage to do it in and am told I can make up to 2500 litres for my own use tax-free. I would intend to do the processing correctly with the kit, using the advised additives of 15-20 per cent methanol and .08 per cent sodium hydroxide (caustic soda - I know, be careful!). The advice is to start with 25 per cent normal diesel mix and work it up to 100 per cent bio diesel. Is this a good idea? Will it work? Will it wreck the engine?