It seems it helps to hang them upside down for bit to allow the sludge to really drain, maybe even a little kerosene "cocktail" shaker action to really clean the gooey bits out. I refilled mine with straight 10w but I wish I'd made the 10/15 mix that other members have used for a bit more damping.
Full Disclosure: I siphoned the oil out of my forks to put in a Progressive spring kit and did not dump. Now I wish I had...every once in while I get a slight buzzy sensation that tells me I have grit or dingleberrys in the sludge around the dampers.
