Well here is the link to where I took my info.
This seems to have come about thanks to lots of people sending in tax returns on a weekly basis to overload the system.
http://news.bbc.co.uk/1/hi/programmes/w ... 288920.stm
It does state that if you use less than 2500 litres per year then there is no tax to declare, but it is a bit of a grey area as to if this is used or new cooking oil.
From reading it states that garden shed producers can use it??? Well I take it that if I buy cooking oil and diesel, mix it myself and then pour it into the tank, I am a garden shed producer.
In fact I use the method of buying cooking oil whenever I see it at the right price and keeping it "in stock" then I use roughly 50/50 mix with diesel, no modifications are needed to any of our cars and I realy do think that they run more mpg when cooking oil is in use as it seems to last longer, but this may not be true as I do not keep records of mpg etc (too busy)
My Xantia estate passed it's MOT yesterday and the MOT chap said that it smelt a bit funny but the emmision test was very low.
I have had experience of 2 x cars (not mine) with cooking oil in use at about 85% both suffering siezed fuel pumps one was an AX and the other a Fiat van (citroen engine) On both occasions these happened after the car was left for 2 weeks whilst the owner was away on holiday, so as a caution if I am leaving the car for more than a week without use, I make sure that I run very low on fuel first and top up with some fresh diesel, just in case there is something in this.
I would say that a 50/50 mix is fine and some people I know use about 75 - 90% cooking oil with no troubles, so I would say "go for it" it's cheap motoring, but without the getting one over on the tax man bit, it's not as much fun though.
Regards
Slim