$6.30 here, if the ol girl is moving this summer its on waste oil mix, sad to say.
Ive been using an old airdog lift pump with twin filters (water sep and 2 micron final filter), but it seems the motor gave up on me just this afternoon. I set it up with a draw pipe and hose to pull out of any drain pan or bucket, and pump/ filter it into a 55 gal drum settling tank. Then, i just flip the hoses around to pull off the top layer from the barrel and into the truck/ jerry can. That way it gets filtered in, settled, then filtered on the way out too, so by the time its got to my injection pump, its been through a settling and 7 fuel filters, two of which are also water separators.
I suppose a centrifuge is best, but this was free out of stuff I had laying around. Im going to pull the airdog apart over the next few days and either repair the motor or, more likely, rig it up to run off a drill or some other bigger motor. it was a little sluggish pulling used 15-40, but that airdog is over 13 years old and had over 200k miles on it, so no real complaints...