i also feel the best way to drain it is to remove it from mower.put back the amount of oil you take out.this way you will get all oil out of tranny.some say to use 10-30 syn some use 10-50 syn.i took mine out and replaced a part inside.draining it was easy ,just turn upside down then take oil and measure how much.i poured it in use 1 qt bottles of oil with the window on side around 1.8 qts.some are more or less.