unless I am mistaken the origional diesel engins did not work on biodiesel they worked on veg oil without additives [as my older 3ltr Mercedies does today - its perfectly legal and runs like a dream] and not biodiesel so why not just get old cooking oil and legally sell it on / or use it privately instead of going into biodiesel?

Thanks for the info JM. However I think that there are other considerations noting the age of your vehicle as the newer the engin is the more [usless?] gadgets there are that actually stop the use of pure heavy fat oils I have noted that in cars [usually after J/K reg] only bio-d seems to work but according to mechanics I know it is all to do with the new engin management systems and nothing to do with the basic diesel engin design itself Environmental considerations: As I know it; it is proven that ordinary heavy oil [old/new cooking fat etc] dos not increase pollution any more than bio-d or similar does in a like for like situation The one big consideration is cost; as the ones who control do not want people to drive for free so engins are engineered these days to run on costly fuels as against free cooking oil!

quite frankly, making the fuel oil in one litre quantities is a waste of time. So if you make it in one hundred litre quantities you will need between 15 and 20 litres of meth. Since 100 litres is nigh-on 20 gallons (ish) [pedantmodeon] you can see that you will soon need that 100 litres of meth. And it's cheaper that size anyway. Never mind the conspiracy theory about bio....quite simply the viscosity is the key, and the cleanliness as well. Badly cleaned recently-made bio will damage the injection system. Too-thick (higher viscosity) fuel will cause other problems....such as the amount being injected being lower than needed. Not only that but thicker oil puts the system under greater stress..... And my van runs on 20% vegetable oil, which comes (when mixed with pump-fuel) within the viscosity range of commercial diesel. The emissions are lower (MOT test smoke test) by 30% Every litre of "bio" costs me 63p. The engine has run on that for over 4 years now. No problems. Yet. And storing methanol is something I just won't do. Apart from the toxicity...when it does burn it is not a "visible" flame...so I'll know it when the smoke and pain from my burning flesh tells me.

Quite! Filtration and keeping it warm for the process then separating the mess from the stuff you need.... All to costly and time-consuming. Not to mention disposing of the waste in a legal fashion.....or even in a non-legal fashion. With places now wanting you to BUY their waste oil, and the cost of the meth and the s/hy, I decided it was costing more to make than to run on 20% svo.

Agree I tried making some once using old used cooking oil from a pub (they thought we were insane :) ) with a friend who was doing a PhD on renewable fuel sources. We had a proper licence and everything! What did we make using our mad chemistry skills - a mess!!! oh and tiny amount of something that may have been fuel. Starting with clean oil was more successful but cost wise it was calculated diluting pure oil with diesel was the way forward, it also saved a lot of mess and us blowing up my mates garage :)