Do not remove the plug with the engine not running. You must have the car level, running, between 30 and 50 degrees celcius ( basically cold start with a load on i.e high beams radio and a/c full blast),and the engine in neutral after cycling through all gears(with e-brake set). Once you have all those requirements met you remove the plug. proper fill level should have fluid barely running out of the hole(not the hole in the pan but in the side of the back just above the pan). Fluid for these models is very expensive so price check before draining for an unnecessary service.Also you must have a pump to pump fluid into transmission before it gets over 50 degrees celcius. maybe leave this to the shop or just leave it alone like the label says.