I`m just about to set up. Is the Racor as seen in Josh Tickell`s book still the best way to go? What about using the SpinnerII in vehicle also? How do you guys purge the system after cleaning/changing the filter? I have a CAV and from what I have read, I feel that changing this may bring an end to the need to filter so thoroughly. Is the majority of the problem with gumming up due to bits of food or FFA build-up?
Cheers, eager but...

Whatever way you clean it, the oil must be heated. If you do this over water the rubbish will fall into the hot water below. You will then need only minimal filtration.

If the oil contains oven cleaner (it often does) it will soap up. Just add some acid to bring ph just below neutral then mix with the water to wash out the excess acid.

For RVO, you need a tank with a side outlet so that clean oil can be pulled off leaving the water behind. The hot oil can then be filtered with standard spin-on sump oil filter.

Oil left behind is skimmed off with some water (before barrel is cleaned) and added to the next batch.

I find all this high quality cleaning such a hassle that it's not much more trouble to make biodiesel. Oil needs to be dry but not carefully separated and filtered. Overall needs more kit to process the oil into ester, but car remains standard.

Swings and roundabouts - yer pays yer money etc...

This idea may be impractical but....

What if the WVO was poured into the tank after only passing through a wire mesh to take out the "rocks" to perpaps 200 micron. A series of filters in the vehicle all heated by coolant would bring the WVO down to around 5 micron before entering the injector pump.
Has anyone done this? I havn`t read about such a system. Would it work?

The amount of energy, time, mess involved in pre-filtering bothers me. Could this be a solution? I`m sure I am not the first to come up with this idea.

Your right Lionel, I too have thought of that too but got stuck on the consideration that the filters would load up too soon from the gunk in the oil. I have found that there is a greater concentration of 100 micron and down of stuff.