RF - that drain screw is pretty small. Drilling a hole in a screw would seem to require a tiny hole. Do you warm the oil before sucking it thru the screw?
Sorry, I was away during the Holidays. Fork oil is pretty "fluid" and we've never warmed it. I would equate is action to being like trans fluid regardless of weight. A good vacuum pulled in from the Schrader valve will suck it in within about 30 seconds. And yes, the hole is small, maybe about 1/16" or so (pretty close to drilled out to the threads). Dad made the little tool back in the early '90s.