I always use my recovery system on hydraulic spills. Spray it with Metasilicate based detergent, let it dwell for a bit, then hit it with a surface cleaner, and suck it up. It usually looks amazing immediately after, and often, after being baked and bleached by the Arizona sun, you cannot even tell it was there a month later.
I am not sure of the effectiveness of this on a biodegradable oil, but I would bet it is designed to break down even more easily.