I filter a bit of oil now and then when I have a surplus, it's seived to 200microns into my storage tank anyway whether for bio or not, then dry it, then use a 12v diaphragm pump with a small speed controller to filter through a triple 10" filter rig you can buy of ebay, it's fairly cheap to setup and you can slow filter 20l in about 20 mins or so, depends on how quick or slow you want to do it.
Pump £10-12 ebay
240v - 3/12v controller £10 ebay
Triple filter setup - about £50 on ebay now, was about 20 when I got one.
Mine is all screwed onto a board neat and easy to keep out the way.