Totally unsceintific, AFAIK. Last time I put too much in any turntable, I rolled up a strip of paper towel and just soaked it up from the top. With a flashlight, there may be a maker inside that shows how much is enough. Just keep some blue masking tape around and keep the area around the well secured so you don't get oil everywhere.
Earlier today I listened to the VPI Traveler and the Rega RP6. The Traveler was not warmed up, nor was the AR tube phono pre, so the whole thing was congested and confusing. Literally. I felt like I was on Crack or something. After a half a side I told the guy I'd make an appt and come back when things were warmed up more. The RP6 was warmed up, as was it's preamp, and was every bit as snappy as Brit hifi is supposed to be, but it definitely missed the tonality that the VPI nailed. Still, not even remotely a 1:1 comparison. The dealer, though, had sold 6 Travelers in the last week, which was pretty surprising.