I used to pump the oil out with a little plastic 12V electric pump I bought from JC whitney over 40 years ago (It still works!). Then, once when I had the tank off, I drilled a 1/2 hole in the left side bottom, near the front, and brazed a 1/2" (true OD) x 2" pipe extension in the side of the tank. (That might be about 1/4" standard pipe) Now I just take out a plug and drain into a pan with no pump and no mess. By the way, I also found the the location of the breather in the tank top dome ensures a lot of mist gets carried back into the intake air and fouls the air filter. I re-routed the breather to the top back left side of the tank, and that problem is gone too. But frankly, just get a pump (electric or hand operated vacuum plunger) and drain your tank that way. I second that you should at least periodically clean the sludge from the tank. Best to remove the tank, but at least for you will need to remove the large banjo fitting with the screen filter, so you don't damage it. If you use a real paper oil filter (I consider this a "must" addition), there will be a little less sludge and you can run the oil a little longer.