I have heard of taking a bucket of old oil, setting it on a block, take an empty bucket and set beside it and a length of rope from the bottom (inside) of bucket 1 to just inside bucket 2 (near the top) so the wick action sucks the oil out of the "old" bucket and drips only clean oil into the "Clean" bucket.
That said.
Today's oil is not just dead dinosaurs. there are additives and anti-acids and viscosity improvers and so on and I'd not want to use oil that had not been properly re-processed by a proper reprocessing facility. these chemicals 'Wear out" unlike the actual oil itself.