There's another thread with discussion about biodiesel fuels in it
here, have a read of that too. There's a another smaller thread on the topic
here.
If you have a look at the
Biodiesel Association of Australia's Production Facilities page, you'll see where the production plants are and what kind of sources they are using for biodiesel in each. I've used bio fuel in the Northern Territory (wasn't by choice) and found it surprisingly good.
The fear is that fats from cooking oils will clog up the works. It's definitely something to be concerned about - but it's not something that the big companies are ever likely to let happen, mostly because they have a point to prove (that biofuel is safe and good for your car). They need to have a 100% clean record in order to keep producing without bad press. They only need to stuff up once for all the dinosaur-fuel companies to point the finger at the boogey man and scare everyone off again.
The greater fear - and the one we genuinely need to be concerned about - is the home brew biodiesel. I'm absolutely sure that those among us that brew our own take every precaution possible, but I'm also certain that very few of us could afford to replace someone else's fuel system if we fought the legal battle over the fuel, lost (paying the legal costs for both sides).
Home brews are often based on used cooking oil. There's nothing wrong with recycling the cooking oil in this way, but you HAVE to remove the fat from it. I don't know how they separate it - centrifuge, fractional distillation, whatever - but that's equipment most backyarders don't have. I'm betting that basic filtration (multiple times) is about the best we can manage.
With production and "warranty" like that, it is RIGHT to be concerned about backyard operations. If you want to do it yourself, you have to accept that you might let some fats through, that these might form deposits in the fuel lines, injectors, pump etc, and that the cost of replacing just the engine side of the fuel system on a YD25 engine is around $9,000. Tank + other fuel lines is additional (haven't had anyone on the forum actually replace all of this, just the stuff up front for other reasons).
In the end, I am happy for some biodiesel from a big company like Gull to be in my tank, but I won't let any backyard stuff in - regardless of the care taken, mostly because I don't want to have the legal battle to get my car fixed when the fuel supplied by a mate breaks it!
