The transmission flund should be checkeck after the car is driven at least 20 miles. The fluid on the stick should feel hot. If checked before the trans is hot use the bottom add line as the full line to get close. Then double check after hot to verify level. If you overfill the trans and run the car you could aireate the oil and possibly create havock inside the trans. If the level gets to where it starts to contact the moving trans parts when running down the road air will start to enter the fluid. The air then plays havock with a hydraulic system not designed to run on an oil/air mixture. Do you're self a favor and drain the extra fluid off. John