For a test run I pumped the oil out of my power washer cold.  With repeated priming or pumping of the plunger it took 20 minutes to get 20oz. of oil out of the engine so once I used it for my six quarts of oil boat it is going to take quite a while but warming the engine could speed it up quite a bit but it does get the oil out with little/no mess.  It works better than a 12v motorized oil pump I once had that took an hour to get 6 quarts of oil out of a boat engine.  That electric pump was a huge mess will oil leaking out anywhere it could.